Looking for ideas on engine build: NA, stock
02-16-17, 05:57 AM
#1
Looking for ideas on engine build: NA, stock
I am in the process of building a new "stock" engine for my 1992 race SC300 non vvti 2JZGE. If money was not an object, what proven ideas do you have to get more power out of a stock NA 2JZ engine? This is for endurance racing, so reliability must remain. Not looking for huge gains, just some slight increase and maybe better torque on mid range. Here are the limiting factors:
Just looking for ideas. Engine is going together in the next month, hope to test in March and race in April.
Edit: Any other comments on improved reliability are welcomed. I have not researched oil pumps as an example, any experience on improved oil pump is welcomed.
- Must reuse existing intake manifold. Internal mods to it might be allowed depending on how much. Must reuse original throttle body.
- Must reuse existing exhaust manifold. I have gutted the pre cat and replaced the cat with Supra downpipe. Not sure what else can make this part flow better as is.
- Could probably pull off mild cam change, but by letter of rules must stay with original cams. Can't use adjustable timing gears. Dammit.
- Could possibly pull off vvti pistons/rods due to slightly higher compression and less rotating mass (so I hear) but once again by rules would be required to stay stock.
- Could get by with port/polish of head, intake, exhaust manifold if there were benefits. I just don't know if there are any improvements overall by doing these if the limiting factor is still the exhaust or intake manifolds. There are trade offs on porting an NA head so it's not exactly clear, unless somebody has documented results. Most cases of head mods would incorporate a header, which I can't do without taking a hit on points which would kick us out of contention for a win. A header obviously would help, but I can't use one.
- Must maintain stock ECU.
- Edit: Must stay with stock distributor (no ind. coil packs).
- Any other ideas that could be considered that wouldn't sacrifice stock appearance.
Just looking for ideas. Engine is going together in the next month, hope to test in March and race in April.
Edit: Any other comments on improved reliability are welcomed. I have not researched oil pumps as an example, any experience on improved oil pump is welcomed.
Last edited by RXRodger; 02-16-17 at 06:04 AM.
02-16-17, 07:30 AM
#2
Yes they are separate from the manifold, joined with a y pipe pre cat then single out of it. I could run separate twins directly from the two exhaust manifolds, you think it would get the proper balancing/scavenging? Not my area of expertise by a long shot.
02-17-17, 12:09 AM
#3
This isn't going to be a scenario where you will be able to do much more than stock. Money and restriction no object, I'd take a look at the MKIV Supra NA Non-VVTi build that LRG_SOUP did with full ITBs, aftermarket ECU, different cams, head porting and valvetrain work, a custom header, coil ignition system and many other changes. He's running an E85 tune on, I believe, standard 10.0:1 compression. The bottom end is all stock on his engine. He's running the stock W58 5-speed and a TRD 2-Way LSD with 4.272:1 gears. I believe his last dyno after such tremendous investment got him about 305whp on the dyno on E85 or another 100+ octane race fuel. For that investment he probably could have had a VERY powerful turbocharged 2JZ.
But his example doesn't seem to fit in with your restrictions if many things have to be left stock. With so many restrictions I think the best thing is to nearly leave the engine alone other than making sure everything has been maintained and that there aren't any surprise failing sensors or systems. Don't leave an ancient harmonic balancer on there either. Given that this is endurance racing and you'll be at part and wide open throttle a lot of the time I wouldn't even bother with removing the EGR since it will never come on under those engine conditions. There aren't many hopped up NA cam options if any really.
I do recommend maybe getting a new igniter and possibly a new fuel pump and fuel pressure regulator if any of yours are old and tired. Additionally, Iridium spark plugs or whatever the longest-lasting plugs on the market are now for 2JZ-GE's.
The best things I can think of in your case with a nearly stock engine: W58 5-speed, limited slip differential, 4.27 final drive ratio, staggered aftermarket wheels with 255-275 rear rubber and 235-245 front rubber, better driving-oriented front bucket seats with side bolstering, LS400 front brake conversion with some better pads like Hawk HPS or EBC Redstuff... and a fresh clutch.
Other than using an OBX or other similar cat-less header which you seem to be barred from doing I think you've done all you can with a gutted #1 cat and downpipe. You can run whatever catback exhaust that you like be it off the shelf or custom. That won't do much to add power but it might be appealing. Your stock ECU may make the car fuel differently if it doesn't detect what it wants to see from the cats although this might be an issue on CA models which have a #3 O2 sensor under the middle of the car more than Federal models which lack this until 1996 or so.
What are the max speeds that the cars on the course you will be driving usually encounter?
But his example doesn't seem to fit in with your restrictions if many things have to be left stock. With so many restrictions I think the best thing is to nearly leave the engine alone other than making sure everything has been maintained and that there aren't any surprise failing sensors or systems. Don't leave an ancient harmonic balancer on there either. Given that this is endurance racing and you'll be at part and wide open throttle a lot of the time I wouldn't even bother with removing the EGR since it will never come on under those engine conditions. There aren't many hopped up NA cam options if any really.
I do recommend maybe getting a new igniter and possibly a new fuel pump and fuel pressure regulator if any of yours are old and tired. Additionally, Iridium spark plugs or whatever the longest-lasting plugs on the market are now for 2JZ-GE's.
The best things I can think of in your case with a nearly stock engine: W58 5-speed, limited slip differential, 4.27 final drive ratio, staggered aftermarket wheels with 255-275 rear rubber and 235-245 front rubber, better driving-oriented front bucket seats with side bolstering, LS400 front brake conversion with some better pads like Hawk HPS or EBC Redstuff... and a fresh clutch.
Other than using an OBX or other similar cat-less header which you seem to be barred from doing I think you've done all you can with a gutted #1 cat and downpipe. You can run whatever catback exhaust that you like be it off the shelf or custom. That won't do much to add power but it might be appealing. Your stock ECU may make the car fuel differently if it doesn't detect what it wants to see from the cats although this might be an issue on CA models which have a #3 O2 sensor under the middle of the car more than Federal models which lack this until 1996 or so.
What are the max speeds that the cars on the course you will be driving usually encounter?
Last edited by KahnBB6; 02-17-17 at 12:14 AM.
02-20-17, 03:01 PM
#4
Yeah I didn't find anything worth doing on the cams, being NA anyway. I will delete the EGR just to clean up the bay like I did on the one in the car now.
Good idea deal on the igniter. I already have a separate fuel pump and regulator at my surge tank and I have bumped the pressure up a few psi to give a little extra fuel at top end. I always replace the harmonic balancer. All the original ones go bad without exception.
I only wish wish I could run a different diff. Have to run what came in it, the old 4.08. I am running a welded one now, need to build a spare up.
I need to run square just to be able to move tires around. I run either 275/40-17 or 255/40-17 on 9" wheels depending on the tire manufacturers.
When we ran Daytona we saw top speeds after the bus stop before turn in to the infield of a little over 130. That's probably the fastest we will ever see, most other tracks don't have that long of a straight run before a turn.
Good idea deal on the igniter. I already have a separate fuel pump and regulator at my surge tank and I have bumped the pressure up a few psi to give a little extra fuel at top end. I always replace the harmonic balancer. All the original ones go bad without exception.
I only wish wish I could run a different diff. Have to run what came in it, the old 4.08. I am running a welded one now, need to build a spare up.
I need to run square just to be able to move tires around. I run either 275/40-17 or 255/40-17 on 9" wheels depending on the tire manufacturers.
When we ran Daytona we saw top speeds after the bus stop before turn in to the infield of a little over 130. That's probably the fastest we will ever see, most other tracks don't have that long of a straight run before a turn.
Last edited by RXRodger; 02-20-17 at 03:05 PM.
02-20-17, 07:50 PM
#5
^^ It sounds like you're already doing most of what you can with the stock NA engine! It may not overly powerful and the torque may not come into its sweet spot until around 3500-4000rpm but you can make what it has very useable on a track at speed. Where NA power upgrades on a 2JZ are lacking the overall endurance durability when all systems are in good shape is the silver lining.
Since you had a 4.08 in the car originally is your SC300 a factory 5-speed?
If your average track speeds are just over 130 in the straights I would recommend sticking with a 4.08 ratio over the 4.27. It can be argued that since the MKIV Supra NA 5-speed came with 4.27 gears stock until the later production years it's the best gear suited for track use-- I can vouch for how torquey a 2JZ-GE feels at 80-90mph in 5th with a 4.272:1 ratio-- but if you are regularly using 4th and 5th between 90-130mph I think 4.083:1 would be better. With a W58 and a 4.27 rear you max out below 140mph if I am correct (I don't know the max number via gearing offhand) but with the 4.08 gearing against a W58 you should have up to 148mph or so as a maximum speed at redline.
It is a choice of tradeoffs though. 4.27 can manage speeds up to 130 just fine and you will have more torque available in each gear for better catch-up acceleration. 4.08 would allow you to hang at very high speeds at a slightly lower max rpm though.
Don't get me wrong: I love the NA/5-speed/4.27 combination for the street and reasonable highway cruising but for a car that sees regular track duty where very high speeds are maintained I think the 4.08 might be the best choice. But it depends on where you like your powerband sweet spot to be.
Your rear tire diameter if above 255 will also contribute to a few more mph. 275 especially. I ran 275's a few years ago. Currently I'm on 255/40-17's in the rear. Very soon I will be going back to 275/40-17. My rear wheels are 17x9.5. If your aim is to reach higher speeds and maintain them over several laps I think 275 is the way to go for top speed although 255 diameter will offer the best acceleration overall.
If you aren't running a Yellr Yellowbox V4 speedo corrector I highly recommend one. Plug and play with an available SC/MKIV specific harness.
Also, given the track use of your car, are you running a thicker heavy duty MKIV style radiator such as one from Mishimoto or Koyo?
There's also a power steering cooler setup to consider to keep your PS fluid from boiling over under very hard use. Stu Hagen (on Supraforums) came up with a driver's side fender-well solution using a custom bracket and a Hayden 678 automatic trans cooler hooked up to the PS lines. I think a thread also came up about this on our sub-forum just the other day using an even smaller but thick universal type cooler that also fits our fender-well.
Since you had a 4.08 in the car originally is your SC300 a factory 5-speed?
If your average track speeds are just over 130 in the straights I would recommend sticking with a 4.08 ratio over the 4.27. It can be argued that since the MKIV Supra NA 5-speed came with 4.27 gears stock until the later production years it's the best gear suited for track use-- I can vouch for how torquey a 2JZ-GE feels at 80-90mph in 5th with a 4.272:1 ratio-- but if you are regularly using 4th and 5th between 90-130mph I think 4.083:1 would be better. With a W58 and a 4.27 rear you max out below 140mph if I am correct (I don't know the max number via gearing offhand) but with the 4.08 gearing against a W58 you should have up to 148mph or so as a maximum speed at redline.
It is a choice of tradeoffs though. 4.27 can manage speeds up to 130 just fine and you will have more torque available in each gear for better catch-up acceleration. 4.08 would allow you to hang at very high speeds at a slightly lower max rpm though.
Don't get me wrong: I love the NA/5-speed/4.27 combination for the street and reasonable highway cruising but for a car that sees regular track duty where very high speeds are maintained I think the 4.08 might be the best choice. But it depends on where you like your powerband sweet spot to be.
Your rear tire diameter if above 255 will also contribute to a few more mph. 275 especially. I ran 275's a few years ago. Currently I'm on 255/40-17's in the rear. Very soon I will be going back to 275/40-17. My rear wheels are 17x9.5. If your aim is to reach higher speeds and maintain them over several laps I think 275 is the way to go for top speed although 255 diameter will offer the best acceleration overall.
If you aren't running a Yellr Yellowbox V4 speedo corrector I highly recommend one. Plug and play with an available SC/MKIV specific harness.
Also, given the track use of your car, are you running a thicker heavy duty MKIV style radiator such as one from Mishimoto or Koyo?
There's also a power steering cooler setup to consider to keep your PS fluid from boiling over under very hard use. Stu Hagen (on Supraforums) came up with a driver's side fender-well solution using a custom bracket and a Hayden 678 automatic trans cooler hooked up to the PS lines. I think a thread also came up about this on our sub-forum just the other day using an even smaller but thick universal type cooler that also fits our fender-well.
Last edited by KahnBB6; 02-20-17 at 07:57 PM.
02-20-17, 09:19 PM
#6
Since you had a 4.08 in the car originally is your SC300 a factory 5-speed?
If your average track speeds are just over 130 in the straights I would recommend sticking with a 4.08 ratio over the 4.27. It can be argued that since the MKIV Supra NA 5-speed came with 4.27 gears stock until the later production years it's the best gear suited for track use-- I can vouch for how torquey a 2JZ-GE feels at 80-90mph in 5th with a 4.272:1 ratio-- but if you are regularly using 4th and 5th between 90-130mph I think 4.083:1 would be better. With a W58 and a 4.27 rear you max out below 140mph if I am correct (I don't know the max number via gearing offhand) but with the 4.08 gearing against a W58 you should have up to 148mph or so as a maximum speed at redline.
It is a choice of tradeoffs though. 4.27 can manage speeds up to 130 just fine and you will have more torque available in each gear for better catch-up acceleration. 4.08 would allow you to hang at very high speeds at a slightly lower max rpm though.
Don't get me wrong: I love the NA/5-speed/4.27 combination for the street and reasonable highway cruising but for a car that sees regular track duty where very high speeds are maintained I think the 4.08 might be the best choice. But it depends on where you like your powerband sweet spot to be.
Your rear tire diameter if above 255 will also contribute to a few more mph. 275 especially. I ran 275's a few years ago. Currently I'm on 255/40-17's in the rear. Very soon I will be going back to 275/40-17. My rear wheels are 17x9.5. If your aim is to reach higher speeds and maintain them over several laps I think 275 is the way to go for top speed although 255 diameter will offer the best acceleration overall.
If you aren't running a Yellr Yellowbox V4 speedo corrector I highly recommend one. Plug and play with an available SC/MKIV specific harness.
Also, given the track use of your car, are you running a thicker heavy duty MKIV style radiator such as one from Mishimoto or Koyo?
There's also a power steering cooler setup to consider to keep your PS fluid from boiling over under very hard use. Stu Hagen (on Supraforums) came up with a driver's side fender-well solution using a custom bracket and a Hayden 678 automatic trans cooler hooked up to the PS lines. I think a thread also came up about this on our sub-forum just the other day using an even smaller but thick universal type cooler that also fits our fender-well.
If your average track speeds are just over 130 in the straights I would recommend sticking with a 4.08 ratio over the 4.27. It can be argued that since the MKIV Supra NA 5-speed came with 4.27 gears stock until the later production years it's the best gear suited for track use-- I can vouch for how torquey a 2JZ-GE feels at 80-90mph in 5th with a 4.272:1 ratio-- but if you are regularly using 4th and 5th between 90-130mph I think 4.083:1 would be better. With a W58 and a 4.27 rear you max out below 140mph if I am correct (I don't know the max number via gearing offhand) but with the 4.08 gearing against a W58 you should have up to 148mph or so as a maximum speed at redline.
It is a choice of tradeoffs though. 4.27 can manage speeds up to 130 just fine and you will have more torque available in each gear for better catch-up acceleration. 4.08 would allow you to hang at very high speeds at a slightly lower max rpm though.
Don't get me wrong: I love the NA/5-speed/4.27 combination for the street and reasonable highway cruising but for a car that sees regular track duty where very high speeds are maintained I think the 4.08 might be the best choice. But it depends on where you like your powerband sweet spot to be.
Your rear tire diameter if above 255 will also contribute to a few more mph. 275 especially. I ran 275's a few years ago. Currently I'm on 255/40-17's in the rear. Very soon I will be going back to 275/40-17. My rear wheels are 17x9.5. If your aim is to reach higher speeds and maintain them over several laps I think 275 is the way to go for top speed although 255 diameter will offer the best acceleration overall.
If you aren't running a Yellr Yellowbox V4 speedo corrector I highly recommend one. Plug and play with an available SC/MKIV specific harness.
Also, given the track use of your car, are you running a thicker heavy duty MKIV style radiator such as one from Mishimoto or Koyo?
There's also a power steering cooler setup to consider to keep your PS fluid from boiling over under very hard use. Stu Hagen (on Supraforums) came up with a driver's side fender-well solution using a custom bracket and a Hayden 678 automatic trans cooler hooked up to the PS lines. I think a thread also came up about this on our sub-forum just the other day using an even smaller but thick universal type cooler that also fits our fender-well.
The tire availability at the 180 treadwear limit for the series tends to drive you to either a Nitto NT-05 which is available in 275 or several others that are only available in 255 max in a 17" size. So, there are only those options.
I am not running the speedo corrector that you mention, but I will look into it now that I am aware. Thanks for that suggestion.
I am running the thicker Mishimoto radiator, but I have to take it out before the first race of 2017 because it also is a hit on points which I was able to last year but can't this year because the value of the SC was increased. I have to go back to stock or take a 2 lap penalty.
Great idea on the ps pump, I constantly have issues with boiling the fluid. I will look into this as well, so thanks on that one too.
It didn't come up, but I had coilovers on the car this year, but I have to remove them or take the hit. So, before the first race I have to come up with a shock and spring that will work. Here is the rule, I have to run the same diameter spring as stock, it can be any spring rate, just has to be the same diameter. It can't be a coilover, even a homemade one (i.e. Gixxer Drew) I plan to go to a heavier spring but need to find a matching shock or have one revalved to work with the new spring rate. They are killing me.
Last edited by RXRodger; 02-20-17 at 09:25 PM.
02-21-17, 04:32 AM
#7
Yeesh. The rules for this series are incredibly strict. They really want you to hamper a great chassis just because Lexus decided to take away most of the good hardware from the Japanese market version. I'm sure that a Supra Torsen LSD is also prohibited while the stock Miata next to you that came with a Torsen as a factory option is perfectly legal if it has one. Never mind that this car came with Torsen LSD's in several JDM Soarer models and some Canadian SC400 models.
Even the radiator has to be stock...? The rules actually allow you to install an auxiliary PS cooler?
The LS400 front caliper upgrade is probably not an option then. What about upgrading to 1992-2000 SC400 front and rear calipers and rotors since they were offered on the same model series as your SC300? At the very least you would then have a more balanced braking system where the rotors and calipers aren't SMALLER in the front than in the rear on a 3500lb RWD car.
Hawk HPS Street Pads are probably your best bet for an available performance oriented brake pad that might better resist fade over an OEM brake pad.
As for the suspension, that's rather rough considering most "factory replacement" suspension options aren't really all that impressive.
There are factory replacement Tokico Blue shocks for our SC's if you can find them in stock anywhere. All I find brand new on Tirerack for our cars are KYB GR-2 shocks but I am not sure how those perform over stock. Eibach may still make an SC300/400 direct fit upgrade spring kit (progressive rate probably) but I am not sure on that either.
You *may* be able to order Hypercoil linear-rate springs in the stock SC shock diameters and lengths (front and rear) for a given spring rate when you use a stock-repalcement shock absorber. I'm not sure what both measurements are offhand but if they can be obtained I'd try ordering what you need though shock-shop's website. There are so many Hypercoil sizes with so many rate options it is probably possible but don't hold me to that.
I am going to assume that you are not allowed to use any OEM Supra TT shocks and OEM TT springs or the Supra-spec Bilstein AK1242 and AK1243 shocks that are a direct fit with OEM Supra TT springs (and not just the rest of the Gixxer coilover system).
Sway bar changes I am going to assume are the same deal (not allowed). Just the geometry change from the trunk-anchored stock SC rear swaybar to the subframe mounted MKIV rear swaybar (whether you use a 22mm or 20mm bar) makes a difference.
You might also try messing with an MKIV Supra TT "Lance" four wheel alignment even without suspension changes that nearly mirror a Supra TT's stock rear suspension setup. Once I had the Gixxer suspension, MKIV rear swaybar (22mm version) and LSD installed on the stock SC300 alignment specs I found my car to be very easily tail-happy even with fairly sticky BFGoodrich tires. With a modified Lance alignment changed the behavior of my car to a more dialed in and predictable feel with a small measure of understeer left in for some warning at the limit.
I hope modified alignment settings aren't also deemed illegal for your class.
What is the name of the racing series and class that you are competing in?
Even the radiator has to be stock...? The rules actually allow you to install an auxiliary PS cooler?
The LS400 front caliper upgrade is probably not an option then. What about upgrading to 1992-2000 SC400 front and rear calipers and rotors since they were offered on the same model series as your SC300? At the very least you would then have a more balanced braking system where the rotors and calipers aren't SMALLER in the front than in the rear on a 3500lb RWD car.
Hawk HPS Street Pads are probably your best bet for an available performance oriented brake pad that might better resist fade over an OEM brake pad.
As for the suspension, that's rather rough considering most "factory replacement" suspension options aren't really all that impressive.
There are factory replacement Tokico Blue shocks for our SC's if you can find them in stock anywhere. All I find brand new on Tirerack for our cars are KYB GR-2 shocks but I am not sure how those perform over stock. Eibach may still make an SC300/400 direct fit upgrade spring kit (progressive rate probably) but I am not sure on that either.
You *may* be able to order Hypercoil linear-rate springs in the stock SC shock diameters and lengths (front and rear) for a given spring rate when you use a stock-repalcement shock absorber. I'm not sure what both measurements are offhand but if they can be obtained I'd try ordering what you need though shock-shop's website. There are so many Hypercoil sizes with so many rate options it is probably possible but don't hold me to that.
I am going to assume that you are not allowed to use any OEM Supra TT shocks and OEM TT springs or the Supra-spec Bilstein AK1242 and AK1243 shocks that are a direct fit with OEM Supra TT springs (and not just the rest of the Gixxer coilover system).
Sway bar changes I am going to assume are the same deal (not allowed). Just the geometry change from the trunk-anchored stock SC rear swaybar to the subframe mounted MKIV rear swaybar (whether you use a 22mm or 20mm bar) makes a difference.
You might also try messing with an MKIV Supra TT "Lance" four wheel alignment even without suspension changes that nearly mirror a Supra TT's stock rear suspension setup. Once I had the Gixxer suspension, MKIV rear swaybar (22mm version) and LSD installed on the stock SC300 alignment specs I found my car to be very easily tail-happy even with fairly sticky BFGoodrich tires. With a modified Lance alignment changed the behavior of my car to a more dialed in and predictable feel with a small measure of understeer left in for some warning at the limit.
I hope modified alignment settings aren't also deemed illegal for your class.
What is the name of the racing series and class that you are competing in?
Last edited by KahnBB6; 02-21-17 at 05:17 AM.
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02-21-17, 08:35 AM
#8
They have a 2x rule on brakes so I have already done the LS brake upgrade without penalty which leaves it with one of the best braking combos on the track. No need to do anymore on the brakes. Hawk blues are no where close to being as good as the Raybestos ST-43's. Same for Carbotech XP10's, EBC yellows (they suck). None of those hold a candle to the ST43's.
I have had it on my radar to look into the Tokico and Bilstein shock in combination with a set of Hypercos at an elevated spring rate, maybe something like an 18/10 combination. I think we can get by with something like that, I just haven't had time to do the homework.
Can't change any sway bars without a swap penalty. Can do anything you want on alignment. I have already slotted the front subframe to get full rotation of the camber bolts to get all the camber possible which is only about 2.8-3.0. I need to make some offset bushings for the uca's to get a little more.
I will look at the other items you mention, once again thanks for the input it is appreciated.
I have had it on my radar to look into the Tokico and Bilstein shock in combination with a set of Hypercos at an elevated spring rate, maybe something like an 18/10 combination. I think we can get by with something like that, I just haven't had time to do the homework.
Can't change any sway bars without a swap penalty. Can do anything you want on alignment. I have already slotted the front subframe to get full rotation of the camber bolts to get all the camber possible which is only about 2.8-3.0. I need to make some offset bushings for the uca's to get a little more.
I will look at the other items you mention, once again thanks for the input it is appreciated.
Last edited by RXRodger; 02-21-17 at 08:50 AM.
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