91 DA Revived

Hello Everyone,

I recently came off the dyno and I was somewhat happy with the results more so happy that my build held up with no major issues when done. If it was going to break probably would have already I assume.

I have noticed that many other cars are building boost rather quicker with huge turbos such as Borg Warner S372 and bigger. Im currently running a Precision 6262 Journal Bearing turbo and I am having trouble understanding why may car is making 12 PSI at 8k RPM. I think I should be making boost before then below is my set up. My question is.... Is it the Tune? The car made 388 HP at 11-12 PSI. very linear power band and peaked 388 at 8300 RPM. so it was a very gradual boost climb. I would think it would come on stronger sooner any thoughts.

B18 LS motor
85MM Darton Sleeves
Eagle Rods
Arias Flat top pistons (compression is a little higher)
B16 Head (GSR valvetrain and cams)
Golden Eagle Intake Manifold
SLS top Mount
Precision 6262 Billett Turbo
Stock ignition
LS transmission Wavetrac LSD
Moroso 6qt oil pan
Walbro Intank fuel pump
STR fuel Rail
ID 1000cc Injectors
Tial Wastegate and Blowoff valve
Precision Intercooler 700 WHP rated
Hondata S300 with Boost by gear

Muckman

iTrader: (2)

How is your boost by gear setup? This sounds like its an issue with the boost control system. If your ebc is not setup for 100% duty until the target boost is reached, say a set duty all the time then it will def cause lag like you are experiencing. Post a picture of the boost by gear config of Hondata. What did the tuner say about this?

91 DA Revived

Well the thing is we were starting the tune on the wastegate it has a 12 PSI spring. For some reason Im not reaching 12 PSI until like 7800 RPM then the wastegate is opening. I guess my questions is why is the turbo taking that long to spool to 12 psi????.

Is it turbo lag i would think not im running a 85mm bore car with flat top pistons I figured this engine would have that turbo starting to build big boost at a lower RPM. the boost by gear has not been messed with as of yet can that be a cause to the wastegate openening too soon.

kyden

do you have any boost leaks? my stock sleeve ls/v makes 18psi at 6000 on a 6265.

Black R

QSV?

TheShodan

iTrader: (14)

Part of it is for several reasons.



1)Your LS transmission may "keep you in boost longer", but has the detriment of acceleration compared to other transmissions. Considering that this turbo setup seems geared a lot more towards drag racing (in which the consensus feels that going into 5th gear is a bad thing for whatever reason) , you may feel as though this doesn't affect you more at the drag strip. But on the street, its terrible. The final drive alone is not worth keeping, but this is simply my opinion.

2) You're only running 12 psi on a turbocharger that is geared to run over 65-66lbs/min on over at least 20psi. You're not even close into the efficiency portion of this turbocharger yet, and without increase in boost pressure, you'll continue to have difficulty reaching maximum boost more quickly. I know it may be hard for the noggin to comprehend, but it is a situation in which in order to have better response, you must actually increase boost pressure into the "sweet spot" of efficiency in order to get its maximum effect. Staying relativelyin a low amount of pressure WAY outside the range of what you have, means that reponse, and acceleration will be greatly effected. I would normally attribute this to poor turbo choice for the match/need , or poor execution of "best bang for the buck", but considering again, this is for drag racing, based upon the rest of the setup you've shown, you really need to increase boost pressure to get it to respond more quickly.

3)Topmount manifold. These are geared for top-end power, not response or good "spool up", and are even WORSE on an LS head that cannot flow naturally the type of CFM you need. In the FAQs there is a thread about a couple of individuals that have smaller and mid-framed sized turbochargers (your 6262 is considered to be on the higher end of mid-framed sized turbos) that switched from the topmount to say, a mini-"ram" without changing anything else, and found over 1000rpms of response from before... and this is without changing anything else. But... I'll say it a 3rd time, because your setup is geared towards drag racing, in which top end power is what is more desired, and "spool up" is a concern that's placed on the back burner, your choice of manifold was bad... as long as you understand that it is geared for drag-racing only.. Many people tend to get these manifolds because of easier access to the downpipe and to add a bit of "bling" to their engine bay, but it can hurt response, especially on smaller turbochargers... However, your 6262 is about right for this kind of setup

Perhaps you might want to re-evaluate what you're using the car for. Many people pick up these great deals on parts because they think that they want to be more purpose-built for thier kind of racing, only to find that they don't either go to that event as often, they fell for their friends ideas of what was best for them, or they couldn't continue with other accessories due to budget concerns. I'm not necessarily saying you fit into those categories, but, either way, these 3 items that I addressed look particularly at issues of responsiveness and use of the car.

CLIFFS:

1) Better transmission Gearing
2) Increase boost pressure (especially when using that LS head)
3) Top-mount manifold and its use may need to be re-evaluated.

Hope this helps a bit..

kyden

^^ he has a b16 head on it.

TheShodan

iTrader: (14)

Edited with correction

LS AzZkIkr

Can you post the graph or logs from the tune?

TheShodan

iTrader: (14)

My suggestions go with the implication that the tune itself was correct for his engine

shanebadoo

91 Da Revived, please check your wastegate and boost piping for leaks. Especially the wastegate, I had a faulty v44 that used to do the same thing (ie build boost slowly) I used to hit 18 psi @8400 with a .82 6262, changed the gate to a known good one without issues and now I can hit 18 psi by 5500 ~ thereabout. In addition to what "The Shodan" and others have said, check the gate.

91 DA Revived

I will try to upload the graph tonight only have my phone and it seems to not be letting me go it from here. All points made are valid appreciate the feedback. I am running a 8lb spring in the tial wastegate and so I'm wondering if I should stuff a 12lb in instead to see if it is maybe opening to soon. Shodan if you have an email I can send you a copy of the final dyno sheet if you would like to see the power bank and such. The car will be tracked otherwise on the street it is just for cruising on weekends. The ls trans was probably not the best choice but free made it easier to go with it lol.

Charlie Moua

iTrader: (3)

well said shodan.