Solved my boost problem!!! OH MY GOD THAT'S POWER!!!

[craZed]

A fuel pressure gage is nice to have.

7psi without any intercooler will make more power
than 7psi through a restrictive intercooler

If the limits of the stock cluch is the quikest you have gone,
then your in for a ride.


Try running .5 bar w/out an intercooler
cooler and get some good logs.
And hopefully the cluch wont slip.

[300zxt]

Must of just been bottlenecking hard, oh well live and learn!

[t70]

please don't laugh -- it was embarrasingly small.. but it was cheap -- $50 including piping from a wreckers. It's intercooler from a ford probe. I had forgotten how small the piping was on it when i started back working on the car and just continued. It was definitely too small, it might work on the t28 as the inside diameter is about the same and it would keep your spool time really quick if you used 1 3/4" piping. Though.. i'm not even sure i'd be confident in the abilities of the intercooler in that situation.

[300zxt]

What intercooler was in there intially that was too small? I'd be interested to know the dimensions etc...

[t70]

I didn't mean to say i was running 20 psi.. i was guessing because of the seat of the pants difference between what was 7 psi before and what i had after the intercooler swap -- I have since looked at my pressure guage which is hooked up to the intake plenum after the throttle body and i haven't exceeded 10 psi yet. That being said -- it's a hell of a lot more power at 10 psi now than it was at 7 psi before. Volumetric efficiency has a huge impact on how much power i can generate at what boost pressure.

I'll be perfectly honest -- i don't know if it is a "real" t70. I was told it's a t70 and it's absolutely huge. I have minimal clearance between the inside fenderwall and the housing.. here's a picture i took a long time ago with the camera phone... and one decent one from the top -- it looks closer than it is, there is more vertical space that you can't see.







Images Gallery with PicTiger

On the exhaust side, that is a 3" v-band so I would imagine it is a t70. Now as for afr's etc.. i've had trouble recently with leaning out -- but it's not just under boost... and i've sourced the problem to the external fuel pump loosing suction or possibly a plugged off fuel filter -- i haven't had a chance to get at it today. This problem however was starting to rear its ugly head before the intercooler swap. I've checked my plugs for detonation and they are fine -- nice and amber with no peppering -- so i'm actually pretty much completely losing fuel flow. However, previous to all this when i mapped at 7 psi i cross referenced my boost level with the fuel map and arrived at the conclusion that column 57 is 7psi -- after three or four data logging runs on the wideband. So once i solve this whole fuel suction/filter problem i'm going to re-evaluate map locations again.
As for tuning technique -- i'm terrified of detonation.. so i take one run at full throttle up to third gear, then i shut the engine down and roll to a stop without disengaging the transmission -- ie -- to ensure proper coolant and oil flow through to a stop -- which takes about 45 seconds not using brakes. At that point I immediately pull the plugs and check their color and look for detonation peppering. If i don't have detonation then i advance whatever section of the map i'm tuning 2 degrees and do it again.. if i hit detonation then i retard 2 degrees and call that section tuned for timing. I know you guys are very concerned about the well being of this engine.. but i am being extremely cautious. So if i reach 400 hp or a lean situation at 15 psi or even 12.. so be it.. i don't know exactly where it's going to hit but i am datalogging and plug checking constantly to ensure proper fuel burn and timing.
Finally, Jason asked what kind of intercooler it is -- short of dimensions here is a picture of it when it was mounted in my 85 supra.

Again.. thankyou all for your help and concern.

[FlawleZ]

Surely he has since taken heed to the advice on this thread. However, I would still like to see some good pictures of your turbo as well as what kind of clearance you had.

[SATAN]

You should not guage how much power you are safely able to run by how much your clutch slips :shock: The 420cc injectors will handle 400hp no problem but you are flowing WAY more air than that. IF IT IS A REAL t-70
seriously, if the inducer on your compressor wheel measures 70mm's allthough I dont know why they would match a 70mm comp wheel with a .63 a/r unless it was a p-trim or larger???) and you are running 20psi with 420cc injectors I guarentee you ARE running TOO MUCH BOOST and running way lean. look at the T-70 comp map its more in the range of 600-700hp at 20psi far from 400. hope this pops up. if not go to not2fast and look at the T-70 comp map and see for yourself. If you dont get it after this then I give up from trying to save somone from an expensive mistake.
[/b]

[Jason84NA2T]

t70 wrote: It's a t70 that i baught from a guy who was going to use it on his civic... so the exhaust a/r is small (0.63 as i recall) but I have had the boost at 9 psi and never slipped the clutch even in fifth... so I'm fairly certain that i should be able to push quite a bit more than that. Now, correct me if i'm wrong but if i run 15 psi then i should theoretically double my engine horsepower from what it would be in N/A trim. I.e. -- if the engine has 160 hp to start then i would have 320 hp at 15 psi assuming that the exhaust side of the turbo has good flow. Now, because this is a t70 and not a t3 then maybe an increase of say... 40 hp on that at 15 psi? Those 420cc injectors should easily handle 400 hp and so i should be able to run about 17-18 psi before i start running out of fuel... So.. at the end of this my real question is -- is this out to lunch? Should i be at a lower final boost pressure? Any help is more than appreciated -- i really don't want to re-ring my engine or replace pistons and rods.

Thanks for all the help you guys have given me throughout this build!

What IC did you upgrade to?

14.7PSI will be two atmospheres making a 6.0L engine. As GE noted it's not 100% accurate for HP gains because not everything is 100% efficient.

You can't really judge the airflow and hence theoretical HP increase without a log of either maf voltage or airflow by another means.

I'd agree with 8PSI probably being safe without any fuel adjustments, be very careful with the boost until you do something about more fuel. Only trust wideband datalogs, not the display. What I would like to see done is someone running the stock injectors at a static 60PSI, and raising the TTPmax to let them flow 100% and drilling the holes in the pintle caps out bigger. I believe this would give you about 50-60% more fuel without any injector swap.

Yes, you can always do the same thing with the 420's and have even more fuel. I am probably going to drill my 550's which RX guys have shown to flow over 630cc and be within 2% of each other afterwards.

You'll be out of metering potential on a Z32 maf wll before that though.

Just to re-enforce it... keep AFR's rich and timing null, and you can make 400+ whp on a stock bottom end no problem.

[G-E]

the math isn't that simple

if everything was 100% efficient maybe....

also psi and flow aren't equivalent, like a fuel pump, higher pressure = less flow, the question is how much is the turbo pumping before it starts being a restriction

[t70]

It's a t70 that i baught from a guy who was going to use it on his civic... so the exhaust a/r is small (0.63 as i recall) but I have had the boost at 9 psi and never slipped the clutch even in fifth... so I'm fairly certain that i should be able to push quite a bit more than that. Now, correct me if i'm wrong but if i run 15 psi then i should theoretically double my engine horsepower from what it would be in N/A trim. I.e. -- if the engine has 160 hp to start then i would have 320 hp at 15 psi assuming that the exhaust side of the turbo has good flow. Now, because this is a t70 and not a t3 then maybe an increase of say... 40 hp on that at 15 psi? Those 420cc injectors should easily handle 400 hp and so i should be able to run about 17-18 psi before i start running out of fuel... So.. at the end of this my real question is -- is this out to lunch? Should i be at a lower final boost pressure? Any help is more than appreciated -- i really don't want to re-ring my engine or replace pistons and rods.

Thanks for all the help you guys have given me throughout this build!

[SATAN]

Um, if its an actual T-70 you are running and you are indeed running a true 20psi from it then 420cc injectors are WAY too small. Just be careful and play it safe, and do the math. better than getting too excited and rushing to make power and then end up having to rebuild an expensive engine.

I think 10psi and 420cc injectors is more like what you should be doing. and that is barley even getting your turbo to talk to you.

[t70]

Thanks man! My buddy will be forking over for those and the sbc clutch i would think...

[craZed]

Take what I say with a grain of salt.
I am no expert,most of what i say is intuition.

You may want to look into some of these as well
http://www.redz31.com/polymounts/isolator.html

[t70]

thanks for the warning... i'll heed it well.. i'm only guessing that 20 psi is what it will handle.. i don't know yet... haven't gotten to the limit of the injectors to my knowledge -- wideband told me i leaned out -- but the source of that was the link between the maf and the turbo broke loose because of excessive engine twist on the mounts. Time for some hump hose to the intake from the maf.

[craZed]

I knew your set up.
Its in your sig :wink:

20 psi on a t70 is asking alot out of 420s.
Even with stock heads.

Just becarefull with the boost.
Because you do have more turbo than fuel.