Lex Luthor

What is the exact CR you arrive @ when you finish your calculations Scott?

racing fan

I believe his was 8.8:! not accounting for the squish....

I think I measured my stock tt headgasket to be 1.3mm. I didn't think there would be .4mm of squicsh though... If teh same number carries over to a single tt hg that would put me at 9.2:1 I guess I'll keep it low on pump.

Lex Luthor

So 8.8:1 is what you arrive at? I thought you were saying that it would be lower than 8.6:1, not higher, have I misunderstood you?

motorheaddown

Lex,

I putting together the numbers... I'll let you know what I come up with.

**EDIT**

FYI, based on the 3.2mm total (1.6mm*2) minus hg compression due to bolting the head on (~0.3mm) minus the stock hg thickness (0.3mm), I get a delta increase of deck height equal to ~2.6mm (.10236"). This seems very reasonable against what I measured (not calculated) on my motor before and after installing the hg. My deck clearance increased by 0.084".

If you want to actually *measure* what the increase is, pull a spark plug, get some thick pipe solder and make sure it's at least 0.175" thick. If you can't find some that thick just double the end over, and squeeze it with a pair of pliers until it's in the ball park of 0.175", Then, form the solder into the form of a "J" so that you can get the bent-over end to touch the side of the cylinder wall near the squish area with the piston down . Next, roll the piston through TDC making sure the solder gets trapped in the squish band. Finally, measure the squeezed solder with a micrometer. It's that easy. The stock squish on a GE motor is ~0.058". My guess is that you'll measure about 0.155" total deck clearance.

**EDIT AGAIN**
Lex, gotta catch a flight home. Give me a day or two to work out the numbers.

-scott

Lex Luthor

Spoke with my tuner yesterday, we have decided to go with Trust's e-Manage with the optional support tool, ignition and injector harnesses, and pressure sensor and harness instead of a full standalone. He's been toying with the e-Man lately on some customer's cars (Silver T3/T4 turbo Integra last time I was there), and has become comfortable with the software already. We agreed that it would do everything that a standalone would do for this application, save some cash, and simplify things (very important to me). Tuners that add a standalone to a VVT-i 2JZ car commonly leave the factory ECU in the car to control everything, and only use the standalone for 16x16 fuel and spark. Some also use the standalone to trigger the VVT-i, but most of these ECU's are just using an output to trigger it as an on-off, which removes the 'intelligence', and makes it like VTEC, so I will let the factory ECU take care of that and keep it working as Toyota intended. The e-manage will therefore only be used for fuel and spark, and is plenty capable of controlling my 55lb injectors with the optional harnesses and software. It will also be used to convert to a speed density metering system so I can delete the airflow meter, which I believe would have been a major restriction. These three parameters were all I needed, and my tuner assures me this decision will not cost me a single horse, i'm told it will still be no problem to hit my pump gas and race gas power goals. Labour will be simpler, we won't have to spend a day wiring up the factory crank trigger to work with the standalone, and we won't have to go with an aftermarket ignition like the DIS4, the IS-style coilpacks will do it. The car will FINALLY be going in for the motor work in two or three weeks, so i'll try to have it done before Englishtown closes for the season. Keep your fingers crossed for me.

- Jon

DIrEctQL

I like the e-man too. With e-man I get to keep my stock ECU.

Is it true that AEM doesn't compensate for weather temp. changes? So it's true that with e-man you don't need to get VPC when upgrading injectors?

Chris

Lex Luthor

Correct, no VPC.

DIrEctQL

Is it true about the AEM not compensating for weather temp?

Chris

racing fan

False... the aem will compensate... you jsut have to give it the correct values. Mine wasn't too far off.... but I've seen other cars that vary mroe.. Not a big deal for a tuner though.

Ebanks

Jon-

Are you really only running 55 lbs/hr? Are you planning on not running a ton of boost?

-Ethan

Lex Luthor

Depends on what you consider a ton .I originally was going with 720's, but felt I didn't need to sacrifice idle quality to hit my power goals, and Lar agrees. I'd like to make just over 500 rwhp @ 18-19 pounds, a 550cc squirter would be enough for that, the 580cc units i'm using will provide me with an extra margin. The short block is limited to around 500rwhp, 600 at the most (VVT-i rods are smaller), so the injectors I chose will be enough to reach the limits of the internals. Later on (after we both have our weddings) I will probably go with a GTE short block from Toyota or do rods and pistons in my GE block, at that point i'll do a full fuel system with dual pumps, dual feed/center return rail, and -8 braided supply with FPR, and 720's, and push the limits of the SP63 as you did. For now I should be able to reliably produce 450+ rwhp on low boost and 500+ rwhp on hi boost and have a fun little street car. The real serious ***** comes later brother...

motorheaddown

Lex,

Sorry for the delay... Here are the numbers:

Based on my estimate of the 0.10236" increase to the deck height and using the following equation (clearance volume = one-cylinder displacement/(compression ratio -1)) from Maximum Boost, p 156, I come to a final CR of 8.086:1. This assumes, of course, that my reference on the TT hg thickness (~1.6mm) is correct. Curt Aigner knows his stuff; so, I'm sticking by it.

Here are the gory details.

The stock clearance volume for 10:1 is 3.38cu in. The cylinder bore is 3.39"; the increase in deck height will increase the clearance volume by the area of the cylinder X the increased height. Consequently, compute the area of the cylinder:

(3.39*3.39/4)*PI = 9.026sq in.

Now, multiply that by the increase deck height to get the volume *added* to the baseline clearance volume:

(9.026 sq in)*0.10236in = 0.9239 cu in.

Next, add the previous result to the baseline CV:

3.38cu in + 0.9239 = 4.304 cu in.

Using the original equation, compute the new compression ratio:

(183.5cu in)/6/(4.304 cu in.) = (CR -1)

CR - 1= 7.086

CR = 7.086 + 1 = 8.086:1

There you have it.

FWIW, using just one TT hg puts the CR at a hair over 9:1. Next time I put together a powerplant that uses meth/water injection, I'll use just one TT hg.

Best regards,
-scott

Lex Luthor

Scott, I went over all your calculations and they do seem to add up, thx for that (glad to see you have Corky's book, he was the man when I was into GN's). If your calcs are on the spot, a hair under 8:1 is a bit lower than I would have normally done on what will be a daily driver, but it will probably allow me to run 20+ lbs on a 94/108 cocktail, or 15-17 pounds and a 70 shot. Until I can go over the math for a couple of days and be totally sure, i'll know that I have a good safety margin either way, and if it's around 8:1......hey, look at the DSM's.....
If one TT HG comes in a hair over 9:1, that's probably ideal for the street but won't allow me to run much over a bar without meth or water (as you mentioned) or propane ( ), so it wouldn't have allowed me to hit my goal with the setup I have now. gadgetSC's SP57 car runs 14lbs on one TT HG, car is real strong and has no problems at that level, I would probably not want to go past 14lbs @ that CR. Hitting 500+ rwhp will require 18+ lbs from the '63, so the only choice was the two stacked HG's, or something aftermarket....but I have heard nothing but good things about the stacked TT setup, and guys have run real quick like that, so I went with it. Hey, at the worst i'll crank it up to 22lbs and embarrass some local big block guys.
Turbo guys are funny.....if I listened to everyone here i'd have too much compression and way too much fuel.....

motorheaddown

Lex,

Hope you don't think I'm being critical. In fact, I think you'll be fine at 8:1. A lot of guys are running there safely. Shoot, DaveH just forwarded me a video of him running 10.69@124, and he runs ~8:1.

My objective is to dispell myths. I don't know how many times I've replied on posts just trying to get some good information out there.

-scott

Lex Luthor

Not critical at all, just informative. I'm all for dispelling myths.