GTM supercharger DYNO

toner123

I think tomorrow I will go dyno my car. I have yet to do that since Sam sent me my new tune a while back. I am interested to see what it does.
Frank

puckshaw

Awesome results! Glad to hear the fluttering has been resolved. I'm real close to putting money down on this kit...

wishihadnav

^^dooo it..you wont be disappointed.

puckshaw

Yeah I'm about to be getting back home from a work assignment in Europe. There's a chance I'll have to go back for a few more months so I need to see how that pans out first.

Kastley85891

I wanted TT from GTM, but now... looks very attractive

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Boosted V8 hunter
2850 lbs and 375WHP

SAM@GTM

David,

Thank you for posting this information up and being part of the solution.

I'd just like to make some comments on your graphs. Your power and torque look outstanding, but the afr looks odd. The target afr is to be 11.8 on average from the point the car goes into open loop. I did notice on your graphs the afr on each run got progressively worse toward the top end. Usually that is an indication that the exhaust sniffer coming off the tailpipe was being pushed backwards. It is very difficult to secure the sniffer in the factory tip. Ideally, it is best to collect afr data right before the cat. Collecting after the cat is ok, so long as you realize that it will read leaner than it actually is. Based on the logs I have from you from the factory widebands right before the cats, the afr was on target (11.8) all the way to redline, which is exactly where we want it to be.

It has been our experience as well that the bends right before the tip on the factory muffler significantly throw off the readings at higher power levels.

At stock power levels, the exhaust gas velocity is low enough to make the turn and still flow somewhat evenly (at least unnoticed by the sniffer). However, as exhaust gas velocity increases at higher horsepower levels, the exhaust gas has more momentum and therefore, doesn't flow through the bend evenly. Therefore, at higher power levels, the sniffer is reading a small quantity of fresh air that fills the low pressure zone created on the inside of the bend between each pulse of exhaust gas.

We've tuned hundreds of Z's and witnessed this phenomenon, time and again.

Here are some visual aids to help you guys understand what we're saying here:

toner123

hey sam on a car with after market exhaust and test pipes is it ok to go from the tail exhaust then or will that also cause to have a lean apearance. Also I would imagine that the 11.8 is the same for both TT and S/C cars. So at what point does the AFR start to become not so optimal to you guys? Finnal question when running data logs I know you mentioned before that they tend to read a little higher then what it really is, so does the little higher varry between each car or is there a set formula you guys use once you get the afr off the ECU. Sorry for all the questions but found this to be a great opertunity to educate my self. Thanks
Frank

SAM@GTM

Yes it is, Ultimately the closer you are to the engine the more accurate samples you will get. with having test pipes in place taking samples out of the tail pipe will be good enough.

Ideally 11.5 to 11.8 is the desirable AFR ration for forced induction, different fuel will require leaner AFR like C16 race gas.

Sam

toner123

Ok so what would be acceptable reading from lets say the Blitz guage unit that reads afr from the ECU for the OBDII port? Just wondering this since I plan on getting it after christmass.
Frank

SAM@GTM

The blitz AFR voltage conversion tables are a little more accurate then the Osiris tables so i would say 10.8 to 11.5 would be spot on .


Sam

Fezzik

Awesome clarification Sam. I would like to thank the whole team at GTM for a wonderful job and the wonderful product I have. I have to recommend to anybody the customer support is awesome. If I ever had a question, they were there to answer it. A good product is nothing without customer support and this company has both!

SAM@GTM

We are glad that we have met your expectations .

Sam

Kastley85891

11:8.1 on FI... these motors love the leaner side, wonder how they would look in SC or TT with E85 12:5.1 few more degrees of timing across the board, the extra TRQ would beery nice on top of an already great graph for both offerings.

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Boosted V8 hunter
2850 lbs and 375WHP

SAM@GTM

Yes they do, The VQ37VHR head combustion design has a lot to do with it. You could never run the same timing tables form the VHR on the DE engine not in million year .

Sam

shumby

weeeeee hehehehehehehehe


I got to get me that BOV ASAP. Sam e-mail sent with the pick up info for the trans. Man theses number look good. A lot of stuff i need to buy now. Cannot wait to get my LTH back on rebuilt trans and the 8 psi pulley and then maybe some VVEL upgrades. man i like toys.



weeeeeeeeeeeeeeeeeeeeeeeehehehehehe

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Originally Posted by SAM@GTM
Engine detonation is not normal and it should never never happen, and whoever told that need to do something else for living .
Sam