noobe here, few questions please.

[87coupe]

i bought an 88 coupe. it's my second supra but the first i sold right after i painted it. never drove it didn't think id like it. now i have this new one and wow i was stupid to get rid of the last one. i LOVE this car lol. anyway, the questions i have.

why does it cut out in first and second gear when i get up to about 15psi. it's like the motor just stops. and is there a way to fix it.

how will a tune affect this kind of car? can i buy something to do it myself or does anyone know of a place i can have it sent out to? i know nothing about these kind of motors so I'm sorry if I'm asking annoying questions.

this motor has about 2k on a rebuild and was told it does have the steel head gasket. how much boost can i safely run with this motor.

feel free to answer any question and thank you for any information.

 

[BoostJunkie]

What are the mods done on it?
If you are cutting out then it sounds like you are hitting fuel cut.

 

[jdub]

1) Fuel cut. Lex AFM = 16-18 psi or go standalone.
2) You will either need a fuel piggyback or go standalone.
3) Depends on the motor...take it to a dyno and find out it's limits.

 

[87coupe]

well I'm not sure on the mods done to it. i know it's a new motor with the steel head gasket. it has a boost control valve(not sure how to even work it) lol the guy told me it should be around 350hp.... it don't feel like 350hp. it's pretty fast but iv had faster and feels more like 300ish. most everything looks stock under the hood. I'm getting ready to tear it down and paint it and do some upgrades. any suggestions would be great.

i know i'm going to sound even dumber then i allready do but what does the below even mean..... ya I'm that dumb with this motor. give me some time I'll get up to speed in a few weeks lol

"1)Fuel cut. Lex AFM = 16-18 psi or go standalone.
2) You will either need a fuel piggyback or go standalone."

thanks for any input.

 

[lewis15498]

well I'm not sure on the mods done to it. i know it's a new motor with the steel head gasket. it has a boost control valve(not sure how to even work it) lol the guy told me it should be around 350hp.... it don't feel like 350hp. it's pretty fast but iv had faster and feels more like 300ish. most everything looks stock under the hood. I'm getting ready to tear it down and paint it and do some upgrades. any suggestions would be great.

i know i'm going to sound even dumber then i allready do but what does the below even mean..... ya I'm that dumb with this motor. give me some time I'll get up to speed in a few weeks lol

"1)Fuel cut. Lex AFM = 16-18 psi or go standalone.
2) You will either need a fuel piggyback or go standalone."

thanks for any input.

He means that your hitting fuel cut b/c your exceeding the max reading from your MAF. Replacing it with a Lexus MAF that has a higher max reading allows you to run more boost. The 7M MAF is only good for about 13 psi

If your running this kind of boost your gonna run into major fuel problems. Hes saying you need either a piggy back fuel controller ( modifys fuel curves by altering signals), or a standalone ECU (replaces factory unit)
Some of the units such as the piggyback MAFT Pro and many of the standalones will allow you to ditch the MAF alltogether and use an AIT and MAP sensors instead, eliminating problem number 1.

Also before you start pumping boost into that motor, i would retorque the head studs. Its probably done right, because you mentioned a MHG but its never a bad idea to check someone elses work. ideal torque ranges from 72-90 lb/ft, i shoot for 80lb/ft, do a search on this and youll get multiple opinions as well as the proper method and order.

 

[87coupe]

thank you for clearing that up. i even understood what you meant is it a specific year lexus i have to use to replace the MAF? thank you for the info. i will price out a stand alone ecu, sounds like that might be a good fix.

 

[jdub]

He means that your hitting fuel cut b/c your exceeding the max reading from your MAF. Replacing it with a Lexus MAF that has a higher max reading allows you to run more boost. The 7M MAF is only good for about 13 psi

If your running this kind of boost your gonna run into major fuel problems. Hes saying you need either a piggy back fuel controller ( modifys fuel curves by altering signals), or a standalone ECU (replaces factory unit)
Some of the units such as the piggyback MAFT Pro and many of the standalones will allow you to ditch the MAF alltogether and use an AIT and MAP sensors instead, eliminating problem number 1.

Also before you start pumping boost into that motor, i would retorque the head studs. Its probably done right, because you mentioned a MHG but its never a bad idea to check someone elses work. ideal torque ranges from 72-90 lb/ft, i shoot for 80lb/ft, do a search on this and youll get multiple opinions as well as the proper method and order.

First of all the 7M uses an AFM (Air Flow Meter), not a MAF...I really wish you guys would keep that straight.
Terminology is important...if I see a guy that can't write a legible sentence using correct terminology, I ignore him.

Second, stock head bolts were tested by Reg Reimer to 72 ft/lbs before getting close to the safety margin for yield strength. This is not "opinion" (and opinion has no place here), it's a fact. If you re-torque stock head bolts, you can safely go to 70-75 ft/lbs...more than that and you are asking for a failure due to the thermal expansion of an aluminum head on a steel block. .

If you are using ARP hardware, use the torque spec on the installation sheet that comes in the packaging...yes, actually read the instructions. You will hear guys spout off all kind of "personal torque" (like Lewis did here) that has no basis in fact. The hearsay that seems to keep being repeated about this motor is a big reason it has such a bad rep...try RTFM before you rely on hearsay.

 

[87coupe]

jdub, thank you for going into detail on you're post. i will do my research before i make purchases and perform work on the motor as i can tell there are plenty of methods and opinions which i'm sure both have merit and i do not want to mess it up. so again thank you for the info. i'm the new guy and just want to enjoy my toy.

 

[lewis15498]

Listen to jdub then, he knows more than me.

 

[92TealSupra]

Where at in Mi are you

 

[87coupe]

lewis15498, i appreciate you're input as well, if you hadn't said what you said then jdub wouldn't have elaborated on his point.... its all good lol thanks for your post.

92tealsupra, i just moved to lake city Michigan.

quick question, i was just driving the car and i notice that just before the boost start to kick in it has a slight bog and hesitation....? any ideas anyone?

thanks

 

[ForcedTorque]

That sounds like the dreaded Lag! Do you know what turbo you have. Lag is usually made up for by the power that comes behind it.

And after going back and looking at your engine picture, it looks to be bone stock, with only a few paint mods. I would doubt that you are near 300 yet. To me, that would cast doubt on everything else the previous owner (also known here as P.O.) had told me. However, if you are running 15lbs of boost, he has done something to it. A shimmed wastegate and 3" exhaust could get you close. Does it have a boost controller? Manual or Electronic? Brand?

 

[87coupe]

it does have a manual boost controller. and a 3 inch exhaust but it's still the stock manifold. i was looking at those t4 turbos on ebay and header for starters. i do know the motor is freshly rebuilt. i seen the paper work on that. other then that i don't know. so the bog and hesitation is just turbo lag? is there a way to fix it?

thanks

 

[BoostJunkie]

Stay away from the Ebay turbos. Check into getting your stock rebuilt with either a 57trim or 60-1. I'm not sure where to get this done from, someone else on here should know. When I bought my supra it had the 57trim done to it. Or there are some people on here sellin their turbo with this mod already done.

 

[87coupe]

oh ok, ya that would make sense and probably a little cheaper to. thanks

 

[ForcedTorque]

Driftmotion does a 57 Trim upgrade for somewhere +-$600. They are a vendor here, or you can go to driftmotion.com. Aaron is the best customer service guy I have found on the internet, and will come as highly recommended as anybody else you will find.

 

[87coupe]

cool thanks for the tip, i will be giving him a call.