Turbo or convertor - which to buy?

[rob86gn]

Dead off the line (only 4-5psi) my car ran 14.45 @98 (20psi). I want to be in the high to mid 12's. I have a stock rebuilt turbo and the rest is on my sig. Should I spend $800 on a TA49 or possibly a GT3255 or buy a custom built convertor that will get me off the line better @ any rpm I want for $600? I recently put the S10 wheel cyl's on to hold better and I've just got some m/t drag radials. Last pass was on BFG radial t/a's. Spun 2nd pretty bad...

Anyone have a GT3255- how is it?

 

[GNVYUS 1]

Considering there is a guy on here doing low 11's on the stock turbo, heads and intercooler, I would say go with the converter like he did. Easy 12's with some boost and M/T drag slicks.

 

[84gnguy]

No offense please..
If you ran a 14.45 @98 w/20 lbs boost something is wrong.
Your MPH should be in the 104-105 MPH range and you should be running a 13.00-13.30 with a mild 60 ft. if not quicker

 

[pontiac69fb]

I agree that something is wrong with his car. My car ran a 14.6 at 96 at 15psi leaving with no boost. My mods include 36 lbers, stock downpipe, intercooler, turbo, k n filter, adjustable fpr, street tires, stock converter, and 93 octane street chip. At 20 psi and leaving with boost I should be in the 13s.

 

[BLACK6PACK]

Lets hope you were running decent gas, cuz with 93 octane and 20lbs of boost your problem could have been knock. I was running 12.80s with the stock turbo, intercooler, and converter on street tires leaving with 1-2 lbs of boost. This was at 21 lbs of boost, 108 chip and race gas. This was with very little tuning. Before throwing money at it, you need to find what your problems are. Do you have a scan tool?

 

[pontiac69fb]

1 more thing your car has some mods done to it plus 5 more pounds of boost and a 14.4 should be what your car runs bone stock. So maybe there are some things you have done to the car that has hurt the performance instead of helped.

 

[Red Regal T]

What was your 60'? Is your convertor the stock D-5? With a stock turbo, you don't need a high stall convertor.

 

[c&cgn]

Stock turbo and M/T DR's is good enough for 12.0's in my car.

You need good tires (m/t dr's are fine) and good gas (I get by with a mix of C16 and 94 pump gas) and 21+psi of boost. Lock your convertor and the car will be in the 12's.

 

[rob86gn]

Thank you for all the responses, my 60' was 2.560- pretty sad. 21psi, 24degress timing, 45lbs fuel press, open exhaust. The car feels good on the top end but getting it going is the problem, it just sucks off the line. I have turbolink and I think everything is where it should be as far as TPS .40, IAC 20, etc. I guess I'll have to play with it some more. I'll take any suggestions...

The previous owner installed a cam in this car which may be affecting the spool up with the stock convertor. I think it's a Poston cam but I don't know for sure. I was running about a 60/40 mix of 104/93 octane with the ultrachip on the 24 degree setting. I'm leaning more toward the convertor at this point.

 

[Hacksaw]

If that cam's not turbo designed it'll cause you fits. That fuel mix should be high enough octane, but you might want to try 100% 104 octane to see.

A bad wastegate solenoid or TPS adjustment will cause bogging.

-Mike H.

 

[trading t/a]

tps should be at least 4.50 at w.o.t.

45 psi of fuel pressure is too much do at least to 42

open exhaust should only help you. Have you done a compression check? Is there oil in your tb? do you have the stock pcv routed to the tb? all these things come into play. The oiling system and pcv sysytem sux!

 

[rob86gn]

PVC is routed to the vaccum block (factory). Checked TPS at wot-good. I suspect the wastegate actuator is bad from the old oil blowing turbo. This turbo was recently rebuilt, Precision didn't say the actuator was bad but who knows, it's oil soaked from before. Compression ranges from 138psi to 160 psi. Only #6 is 160, all the others are between 138 and 140. 150psi is ideal correct?

Since I ran the 14.45 @98 I put S10 brake cylinders, new R44TS plugs, and m/t drag radials and now I can hold 5psi @1500rpm on the street before breaking the tires loose. I also dropped the fuel press to 40 w/line off. My old plugs were bright orange like iron/rust???

 

[trading t/a]

anywhere above 145 is a ok. You may want to try taking a piece of wire and tying the puck closed.***** Be warned that boost will go through the roof. Try building boost with it wired shut if it builds it's a puck/wg problem.

If you do not hear a whine coming from the turbo(ugly sound you'll know it when you hear it) and there's no oiling problem/consumption you should be fine.

 

[GNVYUS 1]

Your high E.T. times are due to your 60ft, and a converter will definitely help that, but not if you are running pig fat.
What are your blm readings when you brake torque it at launching boost?

TPS at WOT only needs to get to 3.8 and then the chip automatically gives you 100% in the fuel table. I was told this by John Spina years ago and Bruce has seconded that statement.

Your compression #'s are a bit to far apart for my taste. Keep an eye on that as you might have some bad rings or a gasket ready to go from the head bolts stretching.

44 plugs are to hot for the boost and timing you are running. Go to at least 43's and even 42's if you plan on running more than 20psi.

I does not sound like you have a scanmaster or a labtop program, do you?

 

[rob86gn]

I have the old version of turbolink. I will try and see what the blm is under load and try tying the puck closed with caution. I will also try colder plugs. Anyone know what the compression psi is supposed to be so I have a benchmark? Thanks.

 

[postal]

Your 60' and Et suck, But those will straighten out if you fix the real problems. I think you have more than one problem.

1. the car is spooling way to slow
2. the mph is low for the boost

I cant think of anything that would cause both other than a really crappy state of tune. I'm not sure of your tunning skills but I never worried about BLM's or any of that. I looked only at WOT o2's and knock. For people to really help you figure out where your problem may be orto figure out what your doing wrong you should make your post as detailed as possible:

o2's
knock
tire pess
air bags and press
open/closed exhaust
plugs/ gap
rpm shift point
boost
burn out procedure
lock up or not
ect...ect..ect

A really good break down will give people the oportunity to try to spot where problems may be instead of just saying that they went faster than you did.

I do agree with every one else. You need to identify whats wrong first before you throw money at speed parts. When you do get it right you should buy and alky kit. A $300 to $400 alky kit will out do a $800 turbo and a $600 convertor combined.

Jason

 

[Robert Walton]

Sorry if I missed an answer to his original question but, I'd do a converter first. Something like a 3000 stall.

 

[Blazer406]

Sorry if I missed an answer to his original question but, I'd do a converter first. Something like a 3000 stall.

I think the consensus was that don't spend money on either...... yet..... after all he was asking for opinions. I can tell you my stock GN is far from tuned.... and first trip to the track.... on stock 12 psi? boost..... launching at about 5 psi...... cut a 2.06 60' and went 9.20 @ a misreable 73 mph..... 140k mile car with a K&N 14" air filter attached to the stock MAF meter. I had 26x10.5x15 ET Streets @ 32 psi. I feel like my MPH sucks cause I have not changed the valve springs out yet (maybe today....I will start that).... and I am still running the stock original 1987 vintage catalytic converter (probably half stopped up). I could have lowered the pressure on the tires.... and spooled up to maybe 10 psi for the launch.....and run maybe 9 flat or a high 8 in the eighth.......

My point is 9.20's is somewhere around 14.50 in the quarter..... which is probably on the slow end for a stock car.... properly tuned.... at 12 psi boost..... on real 215/65/15 street tires....

Get your car running right with the components you have first.... before you jump into anything else......

 

[rob86gn]

I did some testing on the street and recorded some data. O2 was 769mv WOT, I had 7.3 deg spark retard with 93octane and a 20 deg chip. Full exhaust, plugs gapped at .035 R44's. Boost 20psi. I don't think the convertor is a D5 - only stalls to 1500rpm max with drag radials @ 20psi, it does lock though.

I'm definitly buying a converter (anyone use TCS' 12" l/u?), using higher octane fuel next time- probably 111 unleaded.

On the 14.45 run I had radial t/a's with 32psi. Didn't matter because the car wouldn't even spin them until second gear. I also think it's running rich. I have 42.5# with stock turbo @ 45 psi fuel press with line off.

 

[Blazer406]

I did some testing on the street and recorded some data. O2 was 769mv WOT, I had 7.3 deg spark retard with 93octane and a 20 deg chip. Full exhaust, plugs gapped at .035 R44's. Boost 20psi. I don't think the convertor is a D5 - only stalls to 1500rpm max with drag radials @ 20psi, it does lock though.

7.3 deg..... You need to back off the boost to maybe 16 # and make another run..... That 7.3 deg of retard is killing you..... not to mention dangerous.

769 mV @ WOT is not to bad..... if anything it is definately not too rich.... which is kinda puzzling... considering the fuel pressure is kinda high.

Definately pull the plugs out and go at least one step colder as well. R43's do nice.

What kind of fuel pump are you running? Is it hot-wired? With 20# of boost.... your fuel pressure is going past 65 psi.... past where most pumps fall off and by-pass..... definately need a walbro 340 or better..... at least something capable of more pressure w/o bypassing.

Still seems like someting else is not there.

Maybe someone else will hit on it......