ChrisRX8PR

Hello guys,

I need some tips. I just installed my new PT71GTQ and wow, it feels great.

Obviously going from a .84 P-trim small shaft to a .96 Q trim big shaft I can really feel the difference both in power and in Lag. In making the change I feel that the AFR and Timing have a bigger effect on the ramp up towards boost because I spend more time in that range between 0-18 psi than I did before.

What is ideal for AFR and Timing/Split during the ramp up? So far I found that if I keep it at 12.5 from 0-5 psi and then go to 12.0 from 6-9psi falling to low 11's-high 10's from 10psi up it does a little better than how it was set up when I initially swaped turbos.

Before I really didn't need to think of this range because once it hit 5psi it would just ramp up immediately so whether it was at 10.5 or 12.5 AFR in this range really didn't matter much. Now that I spend a reasonable amount of time on the ramp up I would like to optimize it.

How should my ignition be regarding split and timing? I know that retarding ignition helps spool but it also kills hp in that range, which one should I go for? How about AFR's?


I am running E-85 now so take that into account.

Thanks in advance for the help.

Chris

ChrisRX8PR

Anyone have any tips? Personal experience?

I don't expect it to behave like it did with the smaller turbo, I just want it to be as good as it can be.

Thanks

Chris

arghx

iTrader: (3)

wait, retarding ignition helps spool?

ChrisRX8PR

Yes it does. I have a friend that has a clutch switch connected to this ECU and he has it set up so that when that switch is connected the ECU retards ignition to like 30 deg atdc above 3000rpm up to 25psi and it builds this boost in neutral. This way he can leave off the line under boost. Its pretty impressive. Of course this is on the track and I don't think it would help while driving because retarding spool also kills HP so the car would loose all torque.

arghx

iTrader: (3)

ohh you are talking about an anti-lag/two step type of deal. I thought you meant the timing advance curve as boost increases.

ChrisRX8PR

Bump!

Anyone else want to add something?

Rotary?Cool

Fully divided manifold with divided turbine housing, huge exhaust from the turbo back, and v-mount will all eliminate lag. I would imagine a huge non-restrictive air filter wouldn't hurt either. I'm thinking of ditching my old greddy cat back and going with something bigger. I have 3" from turbo to cat back and I think the catback is a little restrictive since its pretty quiet. I'm also going to find the bigest k&n cone filter I can to help increase my spool since I'm stuck with my mani and housing budget wise. I would like to go v-mount as well, way more stealth than the FMIC I have now.

ChrisRX8PR

I have 4" from turbo back, My engine is a renesis so it doesn't allow for a fully divided manifold being that its got 3 exhaust ports instead of two. About the intercooler, mine is a front mount but the way I am running the piping is about as close to a V-mount as you can get.

Mainly I am looking to find what I should be doing AFR and Timing wise to optimize the spool qualities of my current setup to as good as they can be.

Thanks for the tips

Chris

arghx

iTrader: (3)

Howard Coleman (that's his username) may have some input, he's been experimenting with the correlation between EGT and spoolup.

cewrx7r1

iTrader: (2)

Since an AFR of around 12.2 produces the most power, I run it between 0 to 6psi.
Also try increasing timing below 4500 rpm with lower split. I start at 3 split and slowly ramp it up so by 4000 rpm I am at my max split of 12.

ChrisRX8PR

I figured I would post a picture of the new engine and how the new manifold was made. This is as efficient as it is going to get for this car due to the surroundings and the fact that it has 3 runners and this is what I have to work with and the reason I can't run a divided set up.

Any comments suggestions are welcome regarding my original question about reducing lag.

Chris

Dudemaaanownsanrx7

iTrader: (23)

you could get some thermal wrap and wrap the runners all the way to the turbo and then wrap the downpipe. I don't know how much of a difference it will make but keeping the heat inside the pipes will allow maximum exhaust velocity. It will also keep the engine bay cooler.

ChrisRX8PR

Oops I fotgot to say...Everything is completely wrapped, not just to better heat concentration but to keep the adjacent components from being damaged. This picture was taken when the manifold had just been finished so it didn't have wrap at the time.


Thanks for the suggestion.

Chris

Indian

iTrader: (1)

I don't think I've ever seen a mani made like that. Pretty cool. Crispeed or Sean@a-spec should definitely be able to advise you on your answer. I'd like to know too.

ChrisRX8PR

It's a Renesis from an RX-8, that is the reason for the weird 3 runner manifold and the location of the turbo flange.......we just got it in so we will see about power benefits, if any, soon...

Chris

diabolical1

iTrader: (3)

i know you said you're using thermal wrap, but have you considered using a ceramic coating in conjunction with the wrap?

Viking War Hammer

iTrader: (8)

Dudemaaanownsanrx7

iTrader: (23)

are you running an electronic boost control? Keeping the gate closed as long as possible obviously will help.

what kind of power are you putting out? have you been to the dyno?

ChrisRX8PR

I do, I have an E-Boost 2 and it holds the wastegate closed until about 2psi before the boost I want to be at.

Last time I went to the dyno I had the smaller T04S/60mm/.84A/R turbo and I laid down 414whp at 16psi on gas. After the change to E85 and the new PT71GTQ it feels way stronger but winter is here so no more running for a while.

Thanks for the interest.

Chris