GN Cylinder Heads

[AKTURBOTA]

My 89 TTA's engine expired about a month ago, and I have the opportunity of purchasing a fresh 87 GN engine that was built by Weber Racing of North Ridge Ohio. I know that the cylinder heads on a 89 TTA are different than the GN's. My understanding is that the 89 TTA's heads are from a transverse mounted 3.8 litre V6 in order for the engine to fit between the 89 TTA's shock towers. Will a complete 87 GN engine fit in the 89 TTA engine bay?

Mark

 

[72firebird]

I believe I read that GN heads work if you take the AC out. There was a thred about someone putting a stage motor in their TTA but they had to take the AC out to get it to fit. Also TTA heads are from a 3.1L V6 out of late 80s Buicks. You could just put some valve springs and freshen up your TTA heads and put them on the Buick motorm and then sell the GN heads.

 

[TT/Ameasap]

The motor will not fit with those heads....The reason for the other heads was because of the A/C. If your going to run without A/C then everything will work.
BTW do you have any parts from the old TTA motor to sell? I would be interested.

Bo

 

[Razor]

Actually the heads will fit in the engine compartment.. but you wont have any space for the downpipe to make its way through. And you'll need a set of headers.. and the downpipe.. thats the big one.

 

[Grumpy]

bunch of wussie's !!!! IT WILL fit :biggrin:

 

[AKTURBOTA]

Thanks for all your relpies. To reiterate, the gn shortblock with the gn heads will fit in the engine compartment, but will not allow the A/C to be installed, it also will need to use GN headers and the 3" downpipe I presently have will not fit is that correct?

What if I were to recondition my TTA heads and intall them on the GN shortblock. Is there a reduction/increase in compression using TTA heads on a GN shortblock?

Mark

 

[Razor]

If you use GN pistons, the compression will be higher. What this means is you wont hit 16 PSI like you use to anymore without knocking now. It may require a lower timing chip to be used to help with detonation.

If you dont race the car, it may provide you with a much snappier throttle response... but the down side is less boost on the same given octane.

No the GN 3 inch down pipe wont fit without some major massaging

 

[Who Needs 8]

No the GN 3 inch down pipe wont fit without some major massaging

 

[Grumpy]

NOPE !!! need bigger than that !!

 

[Razor]

Thats the Terry Houston alignment tool :biggrin:

 

[postal]

No the GN 3 inch down pipe wont fit without some major massaging

I really wanted to try a four bolt turbine hosing on my TTA. I sat and stared long and hard at my ATR 3" TTA down pipe. There is no damn room in there. I think the 3" dp is a bad design for the stock heads and headers, but theres just no room and thats how they have to do it. If I was going to run that GN short block I would recon the TTA heads, I would also have the combustion chambers worked over to pick a few cc's back up. This would just be valve unshrouding, polishing the chambers, and maybe a slight amount of reshaping / opening them up a bit. You could probably wind up about half way between a standard TTA and a standard GN chamber size. This should be fairly inexpensive and a whole lot less hassel than redoing all your other stuff.

One thing I would find out though is which pistons are in that motor. The common pistons are J&E's or TRW's. One of these brands is 8.0 to 1 and the other is 8.5 to 1 (I can't remember which one is which). Either set will work but if its the 8.0 to 1's then I wouldn't sweat it at all if you had the chambers worked a bit.

HTH: Jason

 

[AKTURBOTA]

Thanks for all your feedback. I am going to abandon the idea about purchasing the GN motor and focus on getting my TTA engine rebuilt. I am considering getting a mild porting job done on the heads as well as matching the intake manifold runners to the cylinder heads. Any other suggestions?

 

[AKTURBOTA]

I am open to all suggestions....

 

[Razor]

Suggestion... as to ???

What are you going to do with it after its built? race it/cruise it/....

What expired.. rod went through side of block?

 

[AKTURBOTA]

I would like to be capable of running low 11's high 10's. Basically a street/strip car. The present motor with is original with bolt on mods that has gone 11.79 at 114.4 in the quarter with TA49. I upgraded to a PT61 with 60# injectors and a 3200 stall TC. I never was able to acheive the previous ET and only matched the MPH with the bigger turbo, so I feel that my engine was getting tired after 13 years of thrashing.

By expired I feel that it blew a head gasket...at mid track it sprayed oil out the dipstick tube and sent a plume of smoke out the back of the car. Once I backed out of it, the smoke abated and stopped. I drove back to the pits and saw the oil all over the drivers side headers. It didn't have any mechanical knocking, didn't overheat, but it runs on what feels like five cylinders.

I feel that it needs a freshening since it has had 13 summers of campaigning at the drag strip.

 

[Razor]

Ha.. I'd throw a set of new head gaskets on it and let er rip another 100 passes easy.

If it MPH the same but not ET.. then you have a converter tuning issue. As MPH is a reflection of HP.

Careful what you ask for. If it has good oil pressure.. just throw a HG on it and not open pandora's box.

What expired was a gasket not the motor. Replace it and keep beating on it.

Wanna do heads on it.. great. Call Champion and get a set.

 

[AKTURBOTA]

Well maybe we will pop off the manifold to see what blew into the lifter valley.
Not having had a head gasket go poof before, I am making a suppostion that that was the case since TurboLink didn't indicate any severe ingition retard, only a drop in boost from 22-23 to 15 PSI. Actually that was the only abnormal statistic in the whole run...the drop in boost pressure. Does this seem like the case?

As for the converter issue, I previously had a PTS 2800 stall and the mile per hour was not any better with the TA49 than with the PT61, and my 60' times went from 1.6-1.7 to 2.1's. There was some tuning issues and definitely underconvertered for the PT61. Well I put in a PTS 3200 and while the track was slick the 60's improved to 1.8's. Each run the 02's were in the high 700's to low 800's and I kept advancing the timing and boost to 26 advance and 23PSI, when the the car laid down at mid track, with the probable head gasket problem. The previous run was 25 degrees of advance and 22PSI. and the car only turned a 12.30 @ 115.2mph. Shouldn't the PT61 be making my car turn 120+? This makes me think that the motor was getting tired. What do you think Razor?

 

[Razor]

Your tuning based on a turbo link file which only gives you as much data as a scanmaster. 1.5 frames per second.There is stuff it will miss. Suggest you get a direct scan for better pictures of what is going on.

Now your turbo question.. reason for a bigger turbo is "IF" you out flowed the current turbo. Arbitrairily putting a PT106 doesnt mean the car will MPH more if the motor wont breathe it. Hence why you slow down going to a bigger turbo at the same boost level. For a stock motor, the 49 will be faster in the lower 20's for boost. This is a case of bigger is not better.

Head Gaskets "HAPPEN" when racing these cars.. you chip away at them until POOF they go. Start Sat moring.. by Sunday afternoon you'll be done. No biggie. My "old" TTA went threw some gaskets.. still is running on the OEM shortblock.. actually drove it a few weeks ago at the track, it ran 11.25.

Dont make a mountain out of a mole hill.. :biggrin: Wanna run.. be ready to wrench on it.

 

[91Bird305]

Just FYI, I have a terry houston downpipe 3" and an 87 GN motor with GN heads and I have A/C. You just have to modify the downpipe and use an 87 GN A/C compressor.

 

[TTA1326]

Just FYI, I have a terry houston downpipe 3" and an 87 GN motor with GN heads and I have A/C. You just have to modify the downpipe and use an 87 GN A/C compressor.

How about some pictures? I've been watching your post in the hybrid section.