New turbo slower times

Clarence Saxon · Jul 22, 2019

My son has a 1983 fox body coupe with a Dart block 347, 10.5-1 compression AFR185 heads, Ford Performance X303 Camshaft, 70mm blow through carburetor turbo, (we only run 114 race fuel only), Lenco 5 speed, 456 gears. It is a race only car, The car ran 10.4 at 129+ mph after installing the turbo. After 2 seasons the turbo went bad (shaft end play), boost level would not stay steady went from 8lb. down to 4 or 5 lbs, back to 8lb on each pass without lifting the throttle. After a fresh rebuild on the engine and replacing the turbo with the same make model and size. We now have a consistent 8lbs of boost throughout the pass but she only ran a best of 11.3 at 123+ mph. Plugs 5,6,7 and 8 are all different shades/color ( yellow insulator Glazing), We can't check plugs 1, 2, 3 or 4 at the track between runs (all new plugs). She has a slight misfire on the big end around the 1000 ft. Has anyone ever had this issue?

TOOLOW91 · Jul 22, 2019

You have a lot going on here . Tune is a major issue In my opinion . What’s the timing ? How are you controlling it

Why so much rear gear even with a Lenco in a turbo car . Usually you’d put something like a 3.27 in a turbo deal

Next is the cam , that thing isn’t even in the ball park for a turbo car and there are huge gains to be made there .

Just my opinion .

a91what · Jul 22, 2019

+1 here, I need pictures of the plugs to say more about the tune, what fuel is used? And wot timing.
The x303 cam has way too much overlap for a turbo.

TOOLOW91 · Jul 22, 2019

a91what said:
+1 here, I need pictures of the plugs to say more about the tune, what fuel is used? And wot timing.
The x303 cam has way too much overlap for a turbo.

Glad we agree . Really only plug pics I’d want are brand new- one hit shut it down and pull them . Other wise would be pointless and Mis leading

Don’t mind my spelling and stuff these days I’m laid up in the hospital and one handing the phone

FastDriver · Jul 23, 2019

Uh... why in the hospital, man? You can't just drop that casually. You ok?

a91what · Jul 23, 2019

This still the same problem you were having before?

MikeH686 · Jul 24, 2019

Just like @TOOLOW91 has said you need to shut the car off and pull the plugs at end of track. When you idle and cruise back to the pits it’s messes everything up. I would also look into possibly adding an air fuel gauge into the down pipe to see if it’s going lean or fat anywhere in the run. What are plugs gapped at? How’s the rest of the ignition system? Still distributor with a single coil? Any ignition box? It’s low boost so I would not think it could be spark blowout. I had that issue in my car but that was at 20+ lbs.

Clarence Saxon · Jul 24, 2019

TOOLOW91 said:
You have a lot going on here . Tune is a major issue In my opinion . What’s the timing ? How are you controlling it

Why so much rear gear even with a Lenco in a turbo car . Usually you’d put something like a 3.27 in a turbo deal

Next is the cam , that thing isn’t even in the ball park for a turbo car and there are huge gains to be made there .

Just my opinion .

Timing is 14 initial, 34 total pulling 1 degree per lb of boost with a MSD BTM box. What cam would you suggest other a custom? It's my son's car I talked him into going with at least the .56, he had a 4.88, I would like him to go to at least a 4.10 like I have in my 351 fox.

Clarence Saxon · Jul 24, 2019

Clarence Saxon said:
Timing is 14 initial, 34 total pulling 1 degree per lb of boost with a MSD BTM box. What cam would you suggest other a custom? It's my son's car I talked him into going with at least the .56, he had a 4.88, I would like him to go to at least a 4.10 like I have in my 351 fox.

I forgot to mention. the AFR has always been 10.8 - 10.9. Last weekend it was 10.1 - 10.3, a bit fat to me.. The plugs have one weekend on them gaped at .25, but to me it's running like a couple of plugs are bad???? We're running 114 race fuel only

a91what · Jul 24, 2019

Lean it out some, run between 11.3-12 in the 10's is way to fat.

Clarence Saxon · Jul 24, 2019

MikeH686 said:
Just like @TOOLOW91 has said you need to shut the car off and pull the plugs at end of track. When you idle and cruise back to the pits it’s messes everything up. I would also look into possibly adding an air fuel gauge into the down pipe to see if it’s going lean or fat anywhere in the run. What are plugs gapped at? How’s the rest of the ignition system? Still distributor with a single coil? Any ignition box? It’s low boost so I would not think it could be spark blowout. I had that issue in my car but that was at 20+ lbs.

We have a full MSD BTM ignition, Plugs are gaped at 025, we had spark blow out with a .35 gap. Plugs have a yellowish tint to them. We have a AFR gauge it was 10.8 - 10.9 now it's 10.1 - 10.3(a bit fat). I agree that we need to shut down and tow her back to the pits. I will try to talk him into that on the first timed run next race.

Clarence Saxon · Jul 24, 2019

a91what said:
Lean it out some, run between 11.3-12 in the 10's is way to fat.

We are a very "low budget" and afraid to go to lean, can't afford another Dart block. Last season we were running very consistent 10.4s at 129+ with 10.8 - 10.9 AFR. Other than blowing head gaskets.

a91what · Jul 24, 2019

again running in the 10AFR range in the gasoline scale is way too rich, you will fuel foul the plugs... 11.3 is considered to be about as rich as you want to run the engine unless you are looking for cylinder cooling.
Is this combo intercooled?

FastDriver · Jul 24, 2019

First I've heard of anyone intentionally running that rich. I catch a little grief occasionally as too conservative, because I like 11.5:1. I like the buffer, and I don't think it makes much of a difference on power. In your case, I'd imagine that's a pretty big difference, though.

TOOLOW91 · Jul 24, 2019

Clarence Saxon said:
Timing is 14 initial, 34 total pulling 1 degree per lb of boost with a MSD BTM box. What cam would you suggest other a custom? It's my son's car I talked him into going with at least the .56, he had a 4.88, I would like him to go to at least a 4.10 like I have in my 351 fox.

So 26 degrees at 8 psi ?

You don’t want all that gear man . It’s not a NA car . max 373s you want the car to make the turbo work and build the heat in the exhaust side to make it spool . I’ll bet you you can get After it big time on the launch and then it will pick up mph big time out the back with a gear change . We went 4.90s to the 1/8 mile with a 3.60 rear gear ...

You keep saying yellowish tint on the plugs does nothing for anyone . In order to get a true plug read you must put fresh plugs in . Make a hit and shut it down and pull them . End of story . Not trying to sound like an ass but anything else you do youre waisting your time trying to read a plug . You can’t come on here asking for a solution and then say you consider getting your son to try this or that when people are offering you a solution.

I’d bet my life on it a stock cam with that turbo would pick up over that x cam you got in it . For 350 bucks the custom cam route would make a huge difference in how it runs and then using the cam to bleed off cyl pressure would open up the tuning window some as well . I’m no pro but have been around a bit .

TOOLOW91 · Jul 24, 2019

FastDriver said:
First I've heard of anyone intentionally running that rich. I catch a little grief occasionally as too conservative, because I like 11.5:1. I like the buffer, and I don't think it makes much of a difference on power. In your case, I'd imagine that's a pretty big difference, though.

Compression is great esp if he had a cam to work with what he’s trying to do with the combo.

TOOLOW91 · Jul 24, 2019

Clarence Saxon said:
We are a very "low budget" and afraid to go to lean, can't afford another Dart block. Last season we were running very consistent 10.4s at 129+ with 10.8 - 10.9 AFR. Other than blowing head gaskets.

I just caught this . If you can’t keep gaskets in it tune up is out to lunch man .

FastDriver · Jul 24, 2019

Right, I was talking about fuel. It's the first time I've heard of anyone preferring less than 11:1.

26* does sound aggressive for pump gas, but I'll bet it's perfectly fine on 114 race gas. My car was still making more power at 15psi at 21-22* of timing. I think at 8 psi, he might be right about total timing, but no way he's right about AFR.

I don't think an X-cam is right for a turbo car, either. I guess he still shouldn't be any slower, though.

FastDriver · Jul 24, 2019

Personally, on race gas, I'd be shooting for 12-12.2 and then whatever timing made it fastest.

TOOLOW91 · Jul 25, 2019

FastDriver said:
Right, I was talking about fuel. It's the first time I've heard of anyone preferring less than 11:1.

26* does sound aggressive for pump gas, but I'll bet it's perfectly fine on 114 race gas. My car was still making more power at 15psi at 21-22* of timing. I think at 8 psi, he might be right about total timing, but no way he's right about AFR.

I don't think an X-cam is right for a turbo car, either. I guess he still shouldn't be any slower, though.

Cam has way to much over lap but I agree with what you’re saying. I’m trying to look at the Combo as a whole .

New turbo slower times

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