Got me a new toy.

[john99gtp]

holy crap!

[SleeperRed90TGp]

so were the mani spacers necessary or a performance option? also what throttle body is that??

 

could you explain the adjustable potentiometer...how does it change fuel cut and how do you use it....does it effect how the car runs when true boost is below fuel cut...like if you run 18 psi actual but the computer only sees 14.7 (with what ever fuel cut eliminator) would the computer see a lower psi than was actually going in all values of boost or does it do anything at WOT or something?

 

finaly what kind of dial in is actually going on?? you just set your boost where you want it and slowy change the fuel cut up to where it doesnt come on anymore?

 

You are an inquisitive young man. Cool

 

No I don't think the spacers are a performance benefit although they do a few things. They insulate somewhat from the heat of the engine, give you much needed room for the harnesses under the manifold( I had one of the cross braces for the fuel rails in my tool box because the harnesses were crushed when I bolted the manifold down. Just gives no worry room) and get the IC hoses out of the way of the waste gate. I also don't think they are detrimental. It's basically adding 1/2 '' to the runner length and all you need is a router to make a pretty precision part. I made these things last year when the 3400 swap was hitting the IC pipe. I knew with a bigger TB I would have problems. Just put them on a few months ago. I would guess mars has more info on them than I do, I think he put them on a while ago an has more experience with them. I haven’t been to the strip since I put the spacers, intake and TB on. I’ am lazy, but I also don't like the heat. But I will get out there. :oops: As far as I am concerned the 3500 manifold is under scrutiny. I really don’t like the inner tube that goes half way down the length of the intake. Looks like there

theory is pull the air into the manifold and then route it back to the rear cylinders I’ll just have to see. I’ve cut the neck off a 3400 intake to accept a larger TB and

hopefully will get it on in a couple months. If I didn’t think I needed them for clearance I wouldn’t have made the spacers.

 

FCD. This is a controversial subject. I was pretty sure what was going on as to why I was running fine and everybody else was taking out there big injectors. So this is just my opinion based on performance with my car only. I just wrote this to a friend a few days ago who asked the same question.

 

FCD does nothing more than restrict (lessen) the voltage signal from the map sensor to the ECM. Most cars fuel cut at about 4.3 to 4.7 volts map signal. Lots of people put zener diodes on rated at 4.3 so the voltage won’t go higher than 4.7 allowing for 5% variance to avoid fuel cut. As far as I know this won’t help the drivability issues. With a pot it restricts the voltage across the board like if the map is putting out 3 volts and the pot is reducing that by 1 volt it will also reduce 4 volts to 3 volts or there abouts. Here is where I think we get drivability with big injectors. Less voltage to the ecm less means less open time (pulse width in milliseconds)of the injectors.( you won’t run pig rich as I have heard many times on here) At wide open throttle the ecm goes into open loop (or maybe closed loop I forget which one) and does what it was designed to do as far as pulse width to the injectors. If the EPROM was set to 7ms it will provide 7 ms at WOT. The ecm doesn’t just jump to 7 ms, I am sure it switches to a WOT table and regulates the pulse according to rpm and TPS and so on. It’s like it ignores the lower voltage .Think I got all that correct, been a long time since I studied this subject. As I have stated before as to drive ability. My wife can and will drive my car an she is a hissey. Its got to be perfect and that is with 30# injectors both pintel and muletec 2’s. I do have to fabreze it first cause I smoke.

 

My map voltage with a scan tool is less than 1 volt at idle and under 3 ½ volts a WOT.

Timing seems pretty normal I have seen 36* advance down to 18* @ WOT. I don’t think the reduced voltages has much if any bearing on timing.

 

To install you just solder 2 wires to the pot, cut the center wire on your map sensor put connectors on the wires and put the pot in. (alternate male and female connectors so you can hook the map wire back together should you ever want to) The center wire runs from the map to the pot out of the pot to the ecm. You will have to ohm the pot to get the 2 correct prongs. Just hook the meter to 2 of the prongs and turn the pot you will see where the most resistance is.

 

Dialing in just turn the knob until it runs best.

 

 

Potentiometer

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=271-1715

 

Knob, Anything with a ¼ hole and a set screw about 2.00 from RS

 

As far as boost I have never been over 12# with the gt 28. I couldn’t control detonation The spark retard helped to get me to 12# and haven’t been to the track a 12#. Yall have to realize that with your t25 @ what ever psi you can get out of it is nothing like the GT28 at 5#. I have no idea where I’ll be with the new turbo. It’s like starting over cause it puts out so much more volume of air.

 

The TB is off a 99 GMC SUV 5.7 lt. It’s one big mo fo. 71.88mm.

 

Jud

[futuretgper]

thanks for the info!! so with you gt28 did you run the pot? or couldn't you get over 12 anyway (without detonation) so there was no use for the pot!!??

 

keep us updated....you must be running the largest turbo on TGP yet!! i dunno what jeff m is running though?? his 450hp claim makes you think!!

[Jcrow]

When you say spark retard, do you mean the built in knock sensor system? Or do you have an after market spark retard?

[SleeperRed90TGp]

thanks for the info!! so with you gt28 did you run the pot? or couldn't you get over 12 anyway (without detonation) so there was no use for the pot!!??

 

keep us updated....you must be running the largest turbo on TGP yet!! i dunno what jeff m is running though?? his 450hp claim makes you think!!

 

450 my ass. Never has backed up anythng said. If I claimed 500Hp would you believe it. :?:

 

The pot is and always has been in use. Won't hardly run without it.

 

12# was on the threshold of detonation. The only way I could run more boost would be race gas, water injection or lower the compression. A bigger IC would also help. which is proly my next project, thats why the 2 1/2" IC pipes.

 

# boost is only 1/2 the equasion. Volum of air is just as important. I have never planed on running more than 10 or 12#. The less # you can use the cooler the charge ie at 12# your turbo might put out 250 CFM at 200*, at 10# with the GT3076 the CFM could be over 400 yet at a cooler temp. the trick is to get the highest volum of air in the cylinders at the lowest PSI. PSI creats heat which you just have to turn around and cool it somehow.

 

 

Jud

[SleeperRed90TGp]

When you say spark retard, do you mean the built in knock sensor system? Or do you have an after market spark retard?

 

It's aftermarket MSD Plus 4 ignition box triggered by an adjustable pressure switch. The box is also adjustable as to how much retard you want to run.

 

I try to run with no KR counts but I usually get 2 or 3 on a run. Any more than that and I'll either have to lower boost or add more retard.

 

Jud

[Jeff M]

keep us updated....you must be running the largest turbo on TGP yet!! i dunno what jeff m is running though?? his 450hp claim makes you think!!

 

450 my ass. Never has backed up anythng said. If I claimed 500Hp would you believe it. :?: Jud

 

Oh you are soooo nice to me sweetie :kiss:

 

Nice custom setup though, keep up the good work and best of luck 8)

 

Jeff M

[kuntzie]

keep us updated....you must be running the largest turbo on TGP yet!! i dunno what jeff m is running though?? his 450hp claim makes you think!!

 

450 my ass. Never has backed up anythng said. If I claimed 500Hp would you believe it. :?: Jud

 

Oh you are soooo nice to me sweetie :kiss:

 

Nice custom setup though' date=' keep up the good work and best of luck 8)

 

Jeff M[/quote']

 

 

so what are you running then Jeff M? PICS of the engine/ turbo putting 450 hp

[Jeff M]

Actually I am going to delete my last post here that had my engine info after a few read it, that in respect of this being Jud's post 8) , even if he treats me so bad

 

Jeff M

[Guest TurboSedan]

Pretty close Joshua

Never heard of an adjustable zener. Good Idea though. Tried a 4.3 zener once, it broke at the solder joint. That wasn’t fun. If your bro was using regular zeners I can see it would be a pia because you would have to change zeners to get the voltage up or down. No fun. There was really no dialing in with the pot. Must have just hit it right. I just go full left turn and it works great.

Jud

 

my brother bought his adjustable zener from M&M Racing. the computer for his Shelby is under the dash; he simply spliced the adjustable zener diode into the MAP sensor leads going to the computer. he put the adjustable zener inside a keyless entry remote as a "casing" which worked out nicely. on his car we actually found fuel cut to be 4.15v. we set the zener to limit voltage to 4.12v and were done with it. the screw was very very touchy....it took us awhile to get it right. we started out by purposely adjusting his grainger valve MBC high enough to hit overboost. he would drive while i sat in the passenger seat with a digital multimeter connected to the MAP sensor wires at the computer. it consistently hit overboost at 4.15v, so i ever so slightly backed it down so it would limit voltage the computer seen to 4.12v. no more overboost. the car is doing great and is running 20psi no problems for months now. he is using +20% injectors, Accufab AFPR with stock base fuel pressure and that is it.

[SleeperRed90TGp]

Hay Joshua that's a pretty cool gaget. Inexpensive too. Wish they had thoese when I put the pot on.

 

I might just get one. Do you know the voltage range like how low it will go?

 

Jud

[TurboGTU]

Yea..with the trim pod, fuel ajustment...the ecm can clean up the mess with the O2 readings. Im still so so with the timming. Though you can change it with the external box. If it works...awsome. Must have taken alot of hit and mis to get it right.

 

 

Your timming seems to go off because your new turbo and engine charicteristics are different from a base LG5. I've done my chip tunning and my new timming seems radical compared to the old chip I had on the GTU with no IC and stock TGP turbo. Even the stock AUAF chip had weak timming for my new setup past 4500rpm and high map. The TG has good timming..but is tune for the stock T25 tooo safe past the 12psi mark. By all means..if you ajust the timming too high with the stock turbo and engine..your pistons will have angel rings or sunroofs . Jeff knows dam well what the stock LG5 setup likes. :read: .so don't mess with the tune if your not different.

[Garrett Powered]

If you do, get some race gas to mix in with your fuel.