Hey everyone, Ive made 330HP @12psi on stock twins and is very happy. I am looking for more but dont want to go single and port yet. What else is there to be done? Different intake manifolds... etc?

Next is fuel pump and boost it to 1 bar/ 14psi but after that IM not too sure.. I want to see how far I can go before I go single and port it.

Current modes are:
PFC
Greddy FMIC
Full SMB 3.5 inch exhaust
HKS Twin SPark
Intake
Profec B II

On Series 8 Rx7.

Thanks

 

next would be larger secondaries and port the wastegate to run around 15psi

 

Throw some 1300ccs injectors in and turn boost up to 17 lbs Of course get it tuned. No need for custom manifolds or any fancy tricks with the stock twins.

 

yup. bigger 2nds, fuel and a good tune! 16 psi is fun!

 

Are you still sequential?

 

Am I the only one who read the thread about how the stock HT12's can only push 15psi effectively?

I don't remember the technical term but as I understand it anything above 15 psi means that the stock turbo's are spinning so fast they actually superheat the air particles they are meant to be compressing... essentially wasting effort and seriously lowering the life expectancy of the turbo's themselves....

I could very well be wrong, and would take no offense what-so-ever to being told I am wrong (so long as an explanation is given to tell how I am wrong).

Any of the technical guru's wanna chime in and shed some light?

 

 

Did a search, came up with these two threads.

https://www.rx7club.com/showthread.p...rbos+max+boost

and

https://www.rx7club.com/showthread.p...rbos+max+boost

Hope it helps a little (as far as the decision to just turn up the boost more).


Cheers,

Levi

 

read what you want.. I have ben runing my car like this for 4 years. The turbos take a beating but make power. I am on my second set in 14000 miles. First set had 60K on them w/ 4000 miles on 15-16 psi. The 2nd set I purchased for $250 w/ 50k on them. Good so far. If you are a bit handy its not terrible to pull an old set. I think for a weekend car or a low boost and high boost daily application it is fine. Just do your homework and properly mod. and port the wastegate. G

 

put her on dyno and see if u make more at 17 then 15 if its a good 20-30 rwhp then u know what to do. juts make sure u have a good

also 330rwhp at 12psi is pretty damn good. have u taken the car to the strip yet?

 

I thought porting the waste gate is only necessary if you catless midpipe? I have the 3.5 inch metal SMB cat alrdy. To run 15 psi which should I do first? Upgrade fuel pump with aeromotive fuel reg or larger secondaries?

 

Yes still seq, heres the dyno graph:

 

that looks a bit lean. who did the tune? i guess thats why you are making the power u did. most afr's i have seen from KAN are below 11. i think thats too low. i;de like to see 11.4 but i think 12 leaves little margin for error, ie cold temps hot temps etc.

 

I agree.. Keep afr's below 11.5. Some say even lower. I also drop a few gallons of 100 octane in the tank for safety. The rx7 store fuel kit w/ 2nd rail, 1600 inj. and fpr is a good choice. Or anything equal to the task. I run 1 walbro 255 in the tank and have it directly wired to the battery w/ an on/off switch to the cockpit so the pump always has 12V. constant. Another safety precaution. Also a poor man's theft deterrent if the switch to turn the pump on is not an easy spot. I have not had any problems other than the relay inline w/ the switch failing(1 time in 14000 miles- 5 second swap). Just keep at least a 1/4 tank of gas so the pump never picks up an air pocket. No problems at all. G

 

If you are looking for the most effeceint power out the car. Open the exhaust and port the wastegate to handle the flow. Restriction= less power. The Rx7 store resonated midpipe is the quietest choice and flows just as good as a straight mid-section.

 

If he is still sequential, will he gain much (if anything) from going non sequential? I only ask because I can easily see myself being in the same situation in a few months (well, as soon as I get my engine back together at least). The only difference will be that I will be doing a medium street port during my rebuild.

 

From 12 to 15 psi a noticeable gain will be made either way. It is hard to keep the vacuum lines in order though w/ a bar+ of boost. G

 

i have been told the stock twins dont last long when you run that kind of boost

 

Very little difference in peak power, mostly it will smooth things out by eliminating the dip at transition.

 

That's what I thought.

 

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