Smaller Turbo or bigger injectors

[Double-L]

I thought I would ask here to see what some of you say, First my GN has 70mm TB, TE70 Turbo, 31/2 down pipe, 491/2 pound injectors, Big front mount intercooler, Little hotter cam than stock, Coated pistons, Headers, Champion stage 2 Alum heads intake, 4 inch air intake with LS1, Tranny has a Art Car 9inch 3500 stall and so on, The intake gasket was leaking and we couldn't get the boost up to 20, Car run 13.30's 150 to 155 60ft. at about 16 to 18, Now we replaced the gaskets and now the guy that is working on it says he can't get the boost down, It is about 28 pounds when he started it and he can't get it under 20, He says it runs great untill you get on it and then it backfires, Spits and bangs, No knock on the knock gauge, He says it needs a smaller turbo, I was wanting to get 65 pound injectors but he said it takes forever to come up on boost with the 3500 stall so would be better to run smaller turbo, I am new to this so what would be best, The car is driven on the street very little but is drove to the strip and back

 

[Blazer406]

What size injectors do you have now? 491/2?

For starters.....you need to fix the boost problem before you make any big decisions...

Is it race gas?

Do you have an audible knock detector.... if no.... I recommend you get one like the Caspers unit.....

Yes a TE70 will spool kinda lazy with a 3500 stall.....

60# injectors are big enough to get you solidly into the 10's should you choose to go that route.....

To me it sounds like you have some 10 second parts...... just need to get a complete combination.....without the proper combination.... those 10 second parts might only get you 12's..... you have to have a good combination.....

Lastly... and most importantly..... WHAT ARE YOUR GOALS? This is the deciding factor weather this or that is too big... or big enough.....

HTH

 

[65vette396]

I thought I would ask here to see what some of you say, First my GN has 70mm TB, TE70 Turbo, 31/2 down pipe, 491/2 pound injectors, Big front mount intercooler, Little hotter cam than stock, Coated pistons, Headers, Champion stage 2 Alum heads intake, 4 inch air intake with LS1, Tranny has a Art Car 9inch 3500 stall and so on, The intake gasket was leaking and we couldn't get the boost up to 20, Car run 13.30's 150 to 155 60ft. at about 16 to 18, Now we replaced the gaskets and now the guy that is working on it says he can't get the boost down, It is about 28 pounds when he started it and he can't get it under 20, He says it runs great untill you get on it and then it backfires, Spits and bangs, No knock on the knock gauge, He says it needs a smaller turbo, I was wanting to get 65 pound injectors but he said it takes forever to come up on boost with the 3500 stall so would be better to run smaller turbo, I am new to this so what would be best, The car is driven on the street very little but is drove to the strip and back

Deff. Buy bigger injectors. I would buy a set of 65's min. 72's preferably. Intake gasket leaking causing boost not to go passed 20 psi.???? 20 psi. on a 70 mm. turbo is probably beyond or right at the limit for a set of 49 1/2 lb. injectors (do they even make such a thing??? are you sure they aren't 009's 43.5 lb. injectors???) That would deff. be passed 100 % duty cycle. If it has a true 3500 stall it shouldn't be that laggy IMHO. Granted my stage car has about 50 extra cubes on you, but I have a 4000 stall and a 88 mm. turbo and it spools pretty much instantly. Sounds like you need a wideband and someone that knows how to tune. Also, gap the plugs down to 26 or so gap and maybe replace coil pack/ module. Are you trying to say the car has been 13.30's @ 150-155 mph. ?????? Cause someone is full of $hit there. My race car has been 9.40's and only traps high 140's to low 150's. It sounds like you need someone that knows what they are doing and do it quickly. Just my opinion, Drew

 

[Blazer406]

.............. couldn't getup to 20, Car run 13.30's 150 to 155 60ft. at about 16 to 18

I took that as a 1.50 to 1.55 60' time ..... not too bad actually... 13.30's suck with all those parts.... but at 16-18 psi boost..... this is totally mis-matched anyway IMHO .... once he gets the boost right... and big enough injectors.... he can start to tune it..... I would recommend starting about 18-20 psi..... eventually working up to upper 20's (if you are on race gas .... or pump gas and alky) ....

 

[65vette396]

I took that as a 1.50 to 1.55 60' time ..... not too bad actually... 13.30's suck with all those parts.... but at 16-18 psi boost..... this is totally mis-matched anyway IMHO .... once he gets the boost right... and big enough injectors.... he can start to tune it..... I would recommend starting about 18-20 psi..... eventually working up to upper 20's (if you are on race gas .... or pump gas and alky) ....

That makes much more sense. My mistake. You are exactly right 13.30s suck even if it pretty much only just had the basic bolt ons, Especially with a 1.5 sixty ft. Car deff. needs bigger injectors and a LOT of tuning it seems. Also, if the car is running a 1.5 sixty, it's not too awful laggy. Drew

 

[Blazer406]

That makes much more sense. My mistake. You are exactly right 13.30s suck even if it pretty much only just had the basic bolt ons, Especially with a 1.5 sixty ft. Car deff. needs bigger injectors and a LOT of tuning it seems. Also, if the car is running a 1.5 sixty, it's not too awful laggy. Drew

that was my thoughts.... if he would have said.... 2.0 60' ...... Lag would definately be a concern... but a 1.50 60' is nothing to sneeze at.... I'd love to get in the 1.5x's with my car at some point.....

 

[Double-L]

Sorry I don't know what I was thinking when I typed 13.30, Let me try and get this right this time, I am new to Grand Nationals, I always raced Chevy, Yes it has 49 1/2 pound injectors, The car ran 11.30's with a best of 11.18 not 13.30, The intake was leaking and the turbo and the headers were leaking and it had a 65mm tb and was running 8 injectors, I had the 80mm tb put on because someone tried to port the stock one and you could see around the buttler fly and I had the x-tra two injectors took off, Yes I have a audible knock detector also has red lights, Have bad hearing, I was running racing fuel, Funny thing is with everything leaking and the stock tb it pulled like a train, Now have everything fixed or it would seem and like I said run great till you get on it, The guy said it is getting way to much air and if I got 65 pounders like I want he said it would blow the heads off the way it is running, He said the car really needs about a TE45a? My goal with the car is just running it on the weekends for fun but to have it very dependable on the street, A high 10 sec. car,

 

[Blazer406]

Sorry I don't know what I was thinking when I typed 13.30, Let me try and get this right this time, I am new to Grand Nationals, I always raced Chevy, Yes it has 49 1/2 pound injectors, The car ran 11.30's with a best of 11.18 not 13.30, The intake was leaking and the turbo and the headers were leaking and it had a 65mm tb and was running 8 injectors, I had the 80mm tb put on because someone tried to port the stock one and you could see around the buttler fly and I had the x-tra two injectors took off, Yes I have a audible knock detector also has red lights, Have bad hearing, I was running racing fuel, Funny thing is with everything leaking and the stock tb it pulled like a train, Now have everything fixed or it would seem and like I said run great till you get on it, The guy said it is getting way to much air and if I got 65 pounders like I want he said it would blow the heads off the way it is running, He said the car really needs about a TE45a? My goal with the car is just running it on the weekends for fun but to have it very dependable on the street, A high 10 sec. car,

11.30's makes alot more sense.... with the 1.50 60' time....

IMHO.... fix all the intake/exhaust leaks... figure out why the boost won't adjust low enough..... trash those injectors before you blow it up.... then you can start afresh tuning.

60# are enough to get you in the 10's.... if your car has already run 11.30's on 16-18 psi boost.... you need more than 60# injectors IMHO.... cause at 28 psi boost.... you might be at 10.50's.... maybe faster.....and 60# injectors mightwould be a little on the small side..... probably need some 83's .... but you will have to get your ECM modified for the low impedance injector drivers.....

IMHO ..... get all that fixed before you decide to go with another turbo......

What was your trap speed with the 11.30 pass...... did I understand you correctly? ... 16-18 psi ... ? Send me the turbo and heads.... you don't need them :wink: I'll send you a smaller turbo and heads..... :wink:

 

[Double-L]

Yes 16 to 18 pounds never could get it to 20, Now we have all the intake/exhaust leaks fixed, Now can't get the boost to turn down under 20, Have manual boost control in car, Trap speed was 119 to 122

 

[Blazer406]

Unless I missed it... you haven't mentioned what type of wastegate you are using..... internal.... or external.... and if external... what type? I assume if it is a TE series turbo... that it could still be internal....

Getting the boost down to around 20 would be a good start to begin to tune from..... but before you go any further.... you really need to step up the injectors... injectors and boost control... would be my first an foremost goals immediately....

Do you have a wideband?

Do you have a scantool? If you don't... I highly recommend DirecScan. It is an awesome tuning tool... requires a laptop... (any 486 or better will do w/o Win XP)... but you get 18 data points per second.... I don't think any of the other popular ones on the market come close to that many datapoints.

 

[Double-L]

Like I said I don't know that much about a Grand National, I have a truck I race or should say play with, I got the car because it was just so nice, The guy that purchased the car new took better care of it from day one than most would, Never been in snow even when new, If it was ever in rain it was by mistake, The guy even gave the car heat and a/c in the summer, Car was inside always, The car was built to drive on the street and race many years ago, He ran only at the big races aboout 4 or 5 times a year, It has 7,000 miles on it now and looks better than my Caddy, He had a smaller turbo, Steel heads on it with the 8 injectors and run 11.30 all day, He stoped racing the car in 1995 and at some time started to update a few things, He was going to race the car again so he put the TE70 turbo, Stage 2 Alum. heads, Comp 1.6 rollers and full rpm kit with bee hive springs, Big front mount intercooler and a few other things and then just got over it and the car never raced again never got around to the injectors, Untill last year, Run the car 4 times then seen water in the oil, Intake gasket, So then changed a few things that I listed, You can turn the boost up from inside the car and under the hood, It has scanmaster and knock gauge, Friend working on it has scan tool, But has been a few years since he has worked and raced Grand National, He wants to go with a small turbo and smaller air intake, A friend that still races says no keep the 4 inch air intake??, That is why I wanted to hear from guys racing now, Thanks for the replys

 

[vader87]

I agree with everything said above! What type of waste gate do you have? Is it internal with a heavy duty actuator? Mine has that and it wil not go below 18 lbs. of boost, but that is where I want it with alky. The adjustment rod is all the way out. If your "mechanic" can't get your boost down it is probably that. If it is an external, check the vacume lines. You have got to get ALL of those leaks fixed! I have the 60lbs. Injectors and I am happy with them but I wish I would have went with 83s :wink:! A smaller turbo will not fix your problem. Keep the big turbo and tune from there. Do not worry about the 4 inch air intake, keep it! Once you get all the leaks fixed and it tuned with bigger injectors, it will be a rocket.