Went single and lost horsepower
08-14-12, 02:24 PM
#52
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I posted the below before I saw that you had some leaks but it still may be something to consider.
Everything suggested may be an issue , but be aware of the fact that a medium to large turbo will not work as well as the twins below a certain RPM, without porting.15psi only talks about pressure, HP is made with flow , if the single isn't up to speed yet (as you said15psi@4500rpm) then you wouldnt get the air to make the power at low RPM,was the engine ported in any way?
Everything suggested may be an issue , but be aware of the fact that a medium to large turbo will not work as well as the twins below a certain RPM, without porting.15psi only talks about pressure, HP is made with flow , if the single isn't up to speed yet (as you said15psi@4500rpm) then you wouldnt get the air to make the power at low RPM,was the engine ported in any way?
08-14-12, 05:09 PM
#54
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I must say thank you for this thread, I also recently went single turbo and while I haven't dyno'ed I felt it should be a little quicker than it is. This lead me to this thread when I was browsing around and I decided to pressure test my system as well, and guess what? Massive hissing/boost leak by the primary injector area as far as I can tell.
I'm running stock primaries with the stock rail tapped for -6AN for my fuel system, KG secondary rail with 2200cc Bosch EV14 injectors. I wish I had a smoke machine, it would be much easier to pinpoint the leak rather than replace all the injector grommets and hope.
Please keep us posted with your results!
I'm running stock primaries with the stock rail tapped for -6AN for my fuel system, KG secondary rail with 2200cc Bosch EV14 injectors. I wish I had a smoke machine, it would be much easier to pinpoint the leak rather than replace all the injector grommets and hope.
Please keep us posted with your results!
08-14-12, 05:45 PM
#55
Im really glad this thread was useful! I will be posting all results and progress so stay tuned.
Its funny how the stock primaries seem to be a weak point. What im still tripping about is how I DIDNT have a fuel leak. I even pressure tested the fuel system after doing the whole setup. 60psi of fuel pressure and I didnt see a leak. It could be due to the direction of resistance. Air is will be pushing out and the fuel is pushing in.
Its funny how the stock primaries seem to be a weak point. What im still tripping about is how I DIDNT have a fuel leak. I even pressure tested the fuel system after doing the whole setup. 60psi of fuel pressure and I didnt see a leak. It could be due to the direction of resistance. Air is will be pushing out and the fuel is pushing in.
08-15-12, 02:38 PM
#56
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Same story for me, pressure tested my fuel system to 50psi and zero leaks, not even a hint of fuel smell. I ordered some new lower grommets and o rings for the injectors today so hopefully this fixes it.
08-15-12, 03:38 PM
#57
the primary rail is sealed, it won't present a leak of fuel unless the injectors or the internal seals in the rails have failed. the grommets simply seal the primary rail to the block to prevent vacuum/boost leaks and usually is a weak point in sealing.
08-19-12, 04:14 PM
#58
I finally got the primaries out and look what I found.
Replaced them and no more major leaks. I drove the car and it feels better. Power is OK but im sure after tweaking the timing maps it should hopefully feel like 400whp. SPool time is better, not great. 14psi by 3800-3900 rpm. Maybe I need to mess with the hks evc IV controller.
Thanks for the input guys, the forum helped me a lot this time.
Replaced them and no more major leaks. I drove the car and it feels better. Power is OK but im sure after tweaking the timing maps it should hopefully feel like 400whp. SPool time is better, not great. 14psi by 3800-3900 rpm. Maybe I need to mess with the hks evc IV controller.
Thanks for the input guys, the forum helped me a lot this time.
08-20-12, 06:23 AM
#60
I can see that you still have your double throttle actuator, do you have this hooked up to a vacuum line? If you do, disconnect it, since I can see that you do not have the solenoid to control it. A vacuum source to the actuator will close the butterflies and block all airflow to to the secondary intake runners.
Just had a NS twins car come in with this same problem, found that the previous "shop" had the double throttle set up this way.
As far as the primary injector grommets, I would say more than half the cars that come in to my shop that have had the engine replaced or the fuel system worked on by other shops have the grommets damaged or missing.
Just had a NS twins car come in with this same problem, found that the previous "shop" had the double throttle set up this way.
As far as the primary injector grommets, I would say more than half the cars that come in to my shop that have had the engine replaced or the fuel system worked on by other shops have the grommets damaged or missing.
Last edited by Banzai-Racing; 08-20-12 at 06:25 AM.
08-20-12, 10:59 AM
#61
The double throttle is capped off. I still need to get a block-off plate for it but for now its ok. Its crazy how easily those grommets get trashed.
Ill look for some more leaks and get that sorted. I still feel like the car a bit too laggy..but this time it may just be me lol
Ill look for some more leaks and get that sorted. I still feel like the car a bit too laggy..but this time it may just be me lol
09-03-12, 03:22 AM
#63
After a few tune tweeks the spool got better with 15psi seen at around 3500 4th gear.
I wasnt aware that the HKS cast makes such a difference in spool time. How much of a benefit would it be to switch over to one of your tubilar manifolds? (power and spool gains?)
09-04-12, 01:09 PM
#65
personally i prefer the reliability of the cast manifolds, they may not be the most efficient but it will outlast your car. even the best fabricated manifolds i see eventually start to leak under heat stress warpage. do you really need boost to snap so quick is the other thing to consider, it makes power less usable in lower gears unless this is a drag car then power is needed wherever you can scrounge it.
09-04-12, 09:45 PM
#67
personally i prefer the reliability of the cast manifolds, they may not be the most efficient but it will outlast your car. even the best fabricated manifolds i see eventually start to leak under heat stress warpage. do you really need boost to snap so quick is the other thing to consider, it makes power less usable in lower gears unless this is a drag car then power is needed wherever you can scrounge it.
Bacon sent me some awsome tuning advice which I followed. Car spools perfect now, but power still feels like 340whp. I just put in some new plugs, so well see how it goes now.... FYI I had 9's before and now I got NGK R7420 10's and 9's.
09-05-12, 09:36 AM
#69
to be honest the response now it good enough for me. Most of my buddies dont believe me when I tell them my turbo is a P-trim journal bearing. I dont neceesary want it to be too snappy especially since its mostly a track car. But if its choking ~30-50whp then I may consider moving to a different tube manifold in the future. For now, I like the setup. Im still messing with the tune and need to figure why the car isnt making power.
Bacon sent me some awsome tuning advice which I followed. Car spools perfect now, but power still feels like 340whp. I just put in some new plugs, so well see how it goes now.... FYI I had 9's before and now I got NGK R7420 10's and 9's.
Bacon sent me some awsome tuning advice which I followed. Car spools perfect now, but power still feels like 340whp. I just put in some new plugs, so well see how it goes now.... FYI I had 9's before and now I got NGK R7420 10's and 9's.
I would figure our the rest or your problems before ordering a manifold..
09-05-12, 11:00 PM
#70
I have only done one back to back vs an HKS cast and it was on a 2nd gen( a more inferior design). I also changed the downpipe from 2.5" to 3.5" at the same time I did the test, and the car made 30 more ft lbs of torque everywhere in the RPM range, I cannot remember how much more HP( same boost pressure, dyno, engine, tune, etc).
I would figure our the rest or your problems before ordering a manifold..
I would figure our the rest or your problems before ordering a manifold..
Anyhow I'm still extremely disappointed .
BTW I re-checked my compression which is even 90psi all around on a hot motor.
09-06-12, 02:42 AM
#72
I know.. before I started a fresh tune I tweaked my old tuners map by adjusting timing to ~15 in upper bands. It made 330whp. Thats why I started fresh.
Im just going off my "butt dyno" when adjusting timing. People have told me 15 is safe with 91 octane so Im going with that again I guess. The only thing bothering me is that if im only gaining ~10hp by upping timing 5 degrees ill rather just keep it at a more conservative level...but I dont think thats the case hopefully.
Im just going off my "butt dyno" when adjusting timing. People have told me 15 is safe with 91 octane so Im going with that again I guess. The only thing bothering me is that if im only gaining ~10hp by upping timing 5 degrees ill rather just keep it at a more conservative level...but I dont think thats the case hopefully.
09-06-12, 02:22 PM
#75
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You guys are creating a really valuable thread.
I'm not racing my car, but I'm constantly tweaking and learning.
I'm the original owner of a '88 vert with mods started a few years ago.
After reading all this, I think a pressure test of the intake system might really be valuable.
Can't wait to see the conclusions here!
I'm not racing my car, but I'm constantly tweaking and learning.
I'm the original owner of a '88 vert with mods started a few years ago.
After reading all this, I think a pressure test of the intake system might really be valuable.
Can't wait to see the conclusions here!