I finally had a chance to get my car dyno tested today at Carolina Dyno in Wilmington, NC. I was only able to put down 370hp at 23.5 psi. My turbo is a bw s366 with the .88 turbine. I have a meth injection system set to come on at 5psi that delivers around 700cc of 50/50 meth. The a/f ration was 11.2 under boost and everything sounded good. It doesn't sound or feel like its hurt but I was expecting around 500hp with this set up. Any ideas what it could be.

other specs are
550/1600 cc injectors
340lph fuel pump
excessive lim
greddy elbow
3 inch turbo back exhaust
10.5 ngk race plugs
hks front mount intercooler
haltech platinum sport 1000
freshly built large street port engine with around 800 miles since rebuild
als seals

 

as you can see on the graph your power dives at 6500 rpm. you are ahead of the power curve before 6500 simply because of the lack of power above 6500 since the chart is a distribution of power V RPM.

BTW, you have only enough injector for 450 hp if you are running 5 bar base pressure (43.5) and no more than 85% duty and 11.2 AFR.




X line starts at 5000 with 500 increments to 7500 at point 6

Y line is % of total power

and yes, w a 366 at 23.5 you should be at or very close to 500

howard

 

On the street it pulls to 8500 rpm with no problem. Are you saying that just by putting some 2000cc secondaries it will pickup that much power. I do understand it would have to be retuned to keep afrs in check

 

"Are you saying that just by putting some 2000cc secondaries it will pickup that much power"

no, i was just cautioning you that you do not have enough injector capacity for your turbo or 500 hp.

clearly looking at the graph below there is something major missing. the upper graph is a composite average of 8 dyno charts around 21- 23 psi.

my guess is some sort of air flow restriction.




x line is rpm starting at 5000 and progressing in 500 steps to 7500.

Y line is hp

howard

 

I thought it may be the air filter so we took it off for one pull but it only gained 2hp. Is there a simple way to track down a restriction or is there a typical area for restriction. I don't have a cat so it can't be that

 

After more research I'm thinking it's an intake restriction. When at the dyno the guy said it was running real rich before boost comes on. Idle has also been a bit rougher than when I first got if back from being built a few weeks ago. I guess I'll just take the charge pipes apart and look for anything inside. The profec b boost controller was also set for 20psi and it's been going to 24 on the gauge which may also be a sign that it's working harder since I never changed it.

 

did you do all the basics--check for exhaust leaks, make sure the ignition system is performing, pressure test for boost leaks?

 

I don't have a pressure tester but on the dyno it didn't have any obvious leaks

 

This thread should be helpful

https://www.rx7club.com/single-turbo...power-1007928/

 

Went back to dyno today. We tested for pressure differential from turbo to intake manifold and it was only 3psi, so no intake restriction. I noticed a flame from under the exhaust manifold after he let off the throttle. There was also a ticking noise which sounds like its a crack even if it's not big enough to see. Would that really cause a near 100hp loss?

 

a primary exhaust leak remains the most likely culprit and it sure looks like you have the symptoms. IDK exactly how much hp loss your exhaust leak might cost but it could be a bunch... a major bunch.

surface grind your manifold and it isn't a bad idea to pony up the large dollars mazda asks for the manifold gaskets. maybe there is an aftermarket gasket?

howard

 

I'm guessing this might have happened the day I went to get my stereo installed and had to drive the car on slushy roads. An eBay manifold at rotary high heat plus possible exposure to ice could have caused the crack. The idle dropped a bit after that day and it seemed different. Looks like it's going to have to come apart to see how bad it is.

 

Did you rebuild the engine due to damage or failure? If so, did you take the turbine housing off the turbo to check for blade damage? Did you do a compression test after the break in on the rebuilt engine? This guy had 454hp with a smaller S360 at the same pressure level: https://www.rx7club.com/single-turbo...2-psi-1055993/

Sounds like maybe the engine might not be in shape although it's a rebuild, something may have happened to one or both rotors.