372whp and 332wtq in snow 4th. 12.0-12.5 afr 6.988psi

The car runs amazing. Perfect setup...The new owner of the setup is enjoying it as well!

 

So, just for interests sake, what did putting an S/C on you is350 do to the fuel economy?

 

I got 1 to 2 miles per gallon better at times. The N/A tune is pig rich....boosting safely leans it out to 11.2-12 and actually keeps fuel economy the same or slightly better. Not kidding

 

Mike, I know you have done other mods, but do you know how much HP you gained by the S/C alone? Also can you estimate your cost, not including your own labour? That is probably unfair to the amount of time and effort you put in. IOW, if a person were to buy all the parts from scratch and follow in your footsteps, what would be the final tally?
Part of me is interested in this, another part thinks it is just a silly idea and that 2nd part can't even believe the 1st part is serious.

 

I hope Mike hasn't given up on this thread completely.

Mike: Did you or the other people you were working with consider one of the smaller vortech s/c's?
Like V9 or V5? If you did, why go with the rotrex instead?
From what I can tell, the Rotrex might be a bit smaller, but the 2 companies seem to measure things differently. Seems like the Vortech V9 should fit, though.

v9 g trim should be capable of upto 825 cfm, which is in excess of what I figure a s/c 3.5l should need (using an online java script, so who knows how accurate it really is).

Still can't find much on is350 supercharging though. Is the HP gain around 50HP like it is with the is250? Or can you do better? I know you said you were getting 370 whp, I think but I don't know what other mods that might have included.

 

Given up? No. I get people msg'ing me every other day with questions so I just reply to their specific concerns.

I was introduced to Rotrex from a BMW friend and was sold on them after seeing HKSIS350 original HKS system using a rotrex blower. Stew in Columbus found a pair of c38-71s and after he pulled the trigger on one I had to buy the other. They are some of the most efficient blowers out there. I esp. like the design using planetary bearings and their c38 models seem to be near bullet proof even with a 3yr warranty.

FWIW, I never had any exhaust mods other than an axleback....fully catted system on stock headers as well. This car MAKES POWER on 7psi! Theres another guy in Texas using a Rotrex system with a fully catless exhaust and headers on his IS350. He is out of fuel at 6psi the system flows so well and hes making so much power. Theres more to be had with more fueling and a way to control it....Someone else has taken that over and I'm confident they will break 400whp on an IS350.
For now, I have moved to a 2urgse motor swap and Greddy roots blower. If I can fab up a worthwhile bracket and pulley design I would like to put a Rotrex on the F motor (similar to icode in japan)...but that's down the road.

 

From what I have been reading, with centrifugal S/C you would normally use a bypass valve, but it seems you were using a bov instead. Might I ask why? I thought of this in particular in response to the mention of people who were going to be trying to add meth injection. It would seem to me that recycling the discharge would make more sense than just venting it if you were injecting methanol. But when I read about it, it sounded like it would reduce lag without injection as well.

 

Feel free to try a recirculated bov or bypass valve but the maf will freak out. Additionally, the IAT will heat up slightly faster even w/ meth when recirculating. I never considered recirculating on this S/C setup. I'm not a fan of the Bosch bypass valve when I knew a traditional bov was more than capable of doing the job at such low boost. IMO, blowing off properly at even low psi is critical to this application....you saw my destroyed C1 Procharger? Didn't take much to do that. Lol

 

I was going to ask this as part of Stew's thread, but since Mike is the one who originally brought it up (AFAIK), I'll ask it here.

This is regarding dropping boost when it gets colder. (what was the issue? misfires?) Why do you think you are getting problems as it gets colder? IAT dropping lower than the ecu is used to and compensates incorrectly?

I think you said you dropped boost to around 4 psi from 7.5. How do you do that? Pulley change? If you just adjusted the BOV, wouldn't it then be blowing off pretty much all the time?

Around here it's so cold for so much of the year, even if I added an S/C I might as well just take the belt off middle of Oct. and not put it back on until mid may. With a bit of snow or ice on the roads (which is damn near all the time) I find myself spinning the tires even with relatively low throttle, and I have blizzaks on, which are supposed to be pretty effective for those kinds of conditions.

 

Mike:
Did you have a fan behind the intercooler?
What kind of clearance is there behind the IC? I believe that IC is the tr8c? So about 3.5" deep?

Thx

 

There's a ton of depth between the bumper beam and condenser/radiator!

Much larger of a FMIC and you'll sacrifice efficiency at such low boost though.

 

Thanks for responding ... and now that I have your attention again, if only briefly, do you have a suspicion of why you had troubles at low temperatures? I can only think that it would be air too cool at the intake. Maybe it is an air pressure thing, but I can't reason that out in my brain.

 

Sure. I don't drive my car from Nov-April because of winters here so I don't have first hand experience with what you're asking. However, I'd speculate it's due to freezing temps and the stock maps having issues adjusting. It's different with turbos as you could experience "boost creep" in very cold temps. The s/c boost is pulley derived so nothing will change in varying temps with regard to boost output. Cold weather on a s/c setup will however make your belt more rigid and could lead to glazing/slipping depending on conditions.

 

Well, that will be bad news for me, should I decide to go ahead. Those days when it is -25 Celsius the belt might not turn at all