I'm still learning my car and not "hammering" it just yet. we did a basline dyno run at 12 psi and it was running pretty lean. as the boost ramps up the AF went from 12.5 to 13.2 before "recovering" and settling back into the high 12s. still a bit too lean and I will definitely need more fuel. the car was tuned in denver (high altitude) and running on meth so it could "get away" with the lean tuning.

this is "Yano's" car that is a built TTiX TT with a beaut of a tiger shark front end plus the CF Jim Hall TT Hood. I knew I would need to do some tuning on the dcar for the lower altitude as the car was tuned mile high in denver.

I talked to Mike of RMCR and the car has a "racetronix" pump and seems to be running about 60 PSI fuel pressure with the 60 lb motron injectors.

would it be wise to step up to the 72 lb injectors, or should the 60's be "enough" without running a crazy duty cycle. I'm also concerned about the volume/pressure of the racetronix pump being able to handle 800 rwhp. I will probably just tune the car for a safe 11.5-12 aft on high boost 17 psi, and use the meth to keep detonation at bay.

also interested in experiences you may have had with tuners on the east coast. I'm considering

Jeff Creech
Keith at Tony's Corvette
ECS

thanks for insights!! I may also just go full boogie and do the A4 switch at the same time, still on the fence. decsions, decsions!!

thanks.

 

FWIW-the fast-i mean fast FI cars-I mean low nines 8 eights on a street setup run the AFR FAT-real fat-fuel is power-this is not a N/A car. How far did you crank up the PE table? If your running that lean with meth-somethings very wrong. If the meth shuts off-your gonna hurt something. 60's are good enough for up to 800rwhp FWIW.

 

your injectors are not the problem especially @ 12psi.
you need to give us more info, was the fuel pressure staying stable?
if so then it needs to be retuned.

 

fuel pressure looked good. I wan't running the meth on this dyno pull, just looking for a a baseline AF which is a bit lean. I agree that a retune maybe all that's needed.

when you are running high boost on meth, should you be looking for about 12 or so AF. I know you can be a bit leaner, but I'm new to the big league. thanks!!

 

thanks. don't know where the PE tables are just yet. this was just a baseline pull without recording anything excep tthe wide band. didn't run the meth on this pull. thanks for the advice about the injectors. I didn't do the "math" but I did figure that they would be enough, especially with the meth.

 

even w/o return line u still should be ok @ that level of psi. i'd install one though

if LTFT are in line then you need to edit your PE or if your have it Boost enrichment

just my .02!

whats funny is that my car runs AR of low tens even high nines @ 6000 plus when the meth starts flowing. it seems that when applying meth the AR s plumet. i personally dont see why any of us TT need to run our cars on the razzers edge.

 

Im going to give a little difference of opinion here. I would first say that you fuel system is def. not sufficient in that a single 255 can not keep up with the demands of a turbo setup. Also, the 60's IMO are not enough for your level. Dont skimp on the fuel system. I would run a second boost referenced 255 pump and RC 74lb high imp injectors. Actually, thats my exact setup, so obviously thats what I am going to suggest. My AFR is at 11.2 and I am not running meth. My injectors are almost maxed out now and Im only running 14psi at the top end. I know this is not what the others are saying, but when it comes to the fuel system, its better to be able to grow and not worry about running lean. Hope this helps.

 

Do you have a wideband? Gauge for the wideband?

I personally would not rely on meth. Tune the car to run without meth.

You have low compression which makes a big difference.

Do you know what the car was tuned with? Does it have a custom OS?

I'd be happy to do some scans for you if it is HPTuners, at least then you would have a better idea whats going on. I'm not so sure that the wideband readings you were getting on the dyno were accurate.

Injector pulse width should give you a clue whats going on.

Give me a call when this weather breaks

 

can you give me a bit more details. Mike was talking about a 2nd "inline pump" with check valves that is activated by an Aeroquip SMU computer. basically an additional pump is added to up the volume and pressure. never heard of it but he's using it alot.

I'm also curious about how the bigger injectors behave. I have 72s in my turbo buick with a double pumper so I know what you mean about not skimping on the fuel system.

thanks for the advice. looking to tune that beeotch up for spring.

 

thanks for the tips, looking to upgrade the fuel system and maybe the injectors. when I plugged in 800 hp at 80% duty cycle with some rough numbers the 72s look about right. rather not push the fuel system beyond what it can delivery.

need some tips on potential upgrades.

APS double pumper
Aeroquip SMU
Kenne Bell Boost a pump
others??

best source for injectors and type

RC
Motron
others??

I'd like to be a bit smarter when I go to the tuner!! thanks.

 

does your car have a BAP?
if you dont then yes i can see that being a problem, i've been there!
i run twin in tank walboro 255 pumps
i prefer to keep it in that tank.
i can hold 78psi @ 19psi of boost.


[IMG][/IMG]

 

Boost a pump. I don't think so. I need to get more info on this car. I think I may just have the single racetronix. I like that setup in the pic. hopefully it's not too bad to install. who makes it?? also curious if anyone has the APS c5 kit.

the boost a pump may be the easiest option. thanks!

 

BAP= Boost A Pump
Made by Kenne Bell.
Raises voltage to pump under boost. The Racetronix harness has provision to tie it in right at the pump. MSD makes a similar product.

Curious: What did the Lingenfelter twin setup run for a fuel pump?

Many have had issues with the Racetronix branded Walbro, and found that the Lingenfelter unit "fixed" the problem, even though it is supposed to be the same pump

It seems to me that if the injector duty cycle is reasonable, then no problem exists. Why fix what aint broke.

If you want to spend money, then just get the ECS fuel system and be done with it.

Plenty of folks have had issues with fuel pressure drop off due to fuel heating after a short period of time.

 

The BAP will definitely help if it's not in there already. What will help, if your fuel pressure isn't dropping, is to boost reference the regulator at the rails.

UPDATE: After doing a search of Yano's earlier posts, you do have a KB BAP.
Arnel

 

oh......

bap and racetronics and losing pressure bla!!!!!!!!!!!!!!!!!!

pump might be takin a dump!

those twin pumps was done by speed inc....it is harder to install as control arms need to be removed. i suggest either ecs or have tom @ speed inc install bosch inliue of your racetronics. take out the assembly and send it to him and itll be good to go!
that is what earl h runs, i have run ......ect ect ect...a little more money then racetronics but imo a better pump.

 

One of the easiest thing people can do, i believe would be to use duel pumps one to each rail with two regulators and one return line. This would solve the * dreded bad pump in tandum or series that leaves you with low pressure and a blown engine at WOT. I haven't or don't know if anyone is doing this on their C5. The also converting to peak and hold injectors would give a better idle when going beyond 60# injectors.

 

like to hear more about high end fuel systems. I believe that I'm probably OK running what I have but it seems the C5s with the "no return" systems are not the best.

on the turbo buicks we have the double pumpers that stage off a hobs switch under boost. problem is, if one pump dies, you lean out and burn holes in pistons.

the Racetronix + kenne bell boost a pump, seems to be enough for 800 rwhp, but I'm wondering if I'm on the edge. clearly the meth will help there to "crutch" the lack of fuel. how many folks are doing 800 at the ground with only a pump + BAP???

not wanting to blow this bad boy up.

 

Or you can get 1 big pump to handle the load and run your own stainless steel lines and fuel rail...

 

Hey Nick,

Where did you get that dual pump setup?

Keith

 

Many? Oddly enough some of those pumps were sent back to LPE for testing only to find there was nothing wrong with them. There was a lot of twisted info about this most of which was re-posted by misinformed people or customers loyal to a competitor's cause.

The Racetronix kit is the #1 selling kit for the C5 by a wide margin. The C5 kit comes with the complete bucket assembly (LPE/GRJ420) along with the harness, drain kit etc.