TTA cylinder heads: chamber volume, exh. ports

[Paul Lohr]

Hello,

Does anyone know what the typical combustion chamber volume is on Turbo Trans Am cylinder heads?

Also, are the exhaust port gaskets the same between the Turbo Trans Am and Grand National cylinder heads?

Thank you for any help,
Paul Lohr

 

[kman71]

Here is some technical info on the TTA that should answer your questions. Also, the exhaust port gaskets are unique to the TTA as the heads are. I just rebuilt one and these are the only gaskets that I could find for them, but work perfectly. Hope the info helps.

Remflex RF13-012 header gaskets

http://www.turbotransam.com/forums/showthread.php?t=4956&page=4


Pontiac contracted the TTA engine with Jeff Beitzel and his PAS Engineering in Van Nuys, California, and the work took place in its 40,000-square-foot City of Industry facility. Once completed, the engines were shipped back to GM, installed in the cars, and then returned to PAS for a brief period of testing and quality-control checks before they were offered to the public for sale. Jeff Beitzel, who was the president of PAS, had his personal 20th Anniversary TTA (one of the 1,555) sent to ASC and made into a convertible. Today it's rumored to be owned by a private collector. Only 1,554, were built, Pontiac created the F-body supercar based upon the GNX engine program. Initially, Pontiac engineers wanted to use an all-aluminum Chevy or Olds 307 V-8 powerplant in the TTA. That plan never came to fruition, so the RPO LC2 3.8L Intercooled Buick Turbo V-6 engine was chosen. The 1989 Turbo Trans Am's utilized a 3.800 in. x 3.400 bore, Buick 231ci/ 3.8L "25526109" engine block, w/ "SG1" cast into the side. A nodular-iron crank, with 4 cross-drilled main bearings, fillet mains and rod journals, plus 6 counterweights PN: 25511229. A set of cast Armasteel 151mm-long cast rods, and special design hypereutectic pistons designed to work at 46.4mm of total compression height to produce a compression ratio of 8.0:1. It was fitted with cylinder heads from the existing traverse V-6 3800 Series I heads, PN: 25536702, which yielded superior combustion chamber design & exhaust flow of the GN/GNX design. It allowed room for the downpipe to fit, and also gave more clearance around the strut towers & A/C box on the firewall. It used a hydraulic roller camshaft, with 192/196-degrees duration at .050, .409/.434 lift, 1.71 intake valves and 1.49-inch exhaust valves, with special 1.65:1 rockers. A crank trigger ignition was used to fire the spark plugs more effectively. The spark plug wires of the TTA are unique, embossed with the 20th Anniversary logo, they have plug shields on their ends to prevent burning. A specialized Garrett T-3 turbocharger w/ a ceramic-impeller, provided a maximum of 16.5 psi boost, fed through a GNX-based 12-fin intercooler to a "CERMATEL" (Ceramic/Aluminum) coated pipe to a 75.5mm MAF, 58mm throttle body, and then forced into an aluminum intake manifold. 91 or greater Octane was mandatory to feed the beast's thrist and protect against detonation. Inside the fuel tank, a baffle surrounds the fuel pump and ensured a steady supply of fuel to the pump during sharp turns, specifically designed for the IMSA (International Motor Sports Association) "Showroom Stock" competition. A high volume electric fuel pump was used to feed fuel to a high-pressure Bosch 237 fuel pressure regulator, and metered out to 6 Bosch 28 lb/hr injectors. A specially recalibrated ECM and custom PROM operated the computer system and maintained the balance effectively. Although there are substantial differences between a stock Turbo TA chip and a stock Grand National chip, the ECMs are identical. The spent gasses were expelled via TTA-specific Stainless steel 3-into-1 headers, down into a high flow catalytic converter, and passed though a 2.5-inch exhaust system with a crossflow muffler, and out through dual, polished stainless steel "splitter" tailpipe extensions, similar in style to those used on the Trans Ams of the late 70's. The engine was seriously underrated at 250 hp. In actuality, the TTA motor reportedly made 301 hp on the PAS engine dyno and 10 to 15 lb-ft higher torque than the advertised 340 lb-ft. Chassis-dyno test results of bone stock cars, yield numbers that correspond with TTAs typically making around 220 HP to the rear wheels. A mid-year change was made to the Turbo TA's plastic turbo inlet tube, and replaced with a durable unit with a clamping rib on either end to keep the hoses attached more securely. (A note to assist in saving your stock one from collapse: cut a short 1" length of 3" dia exhaust pipe and insert it into the end of the inlet tube. It's a perfect fit and will allow tighter clamping forces to be applied) The engine also utilized a horizontally-mounted A/C PF-1218 oil filter with an anti-drainback valve to prevent oil starvation at engine startup. The original TTA's serpentine belt was slightly longer than optimal and was a common malady on stock trim car as the belt stretched with use, heat, and age. All Turbo T/A's came equipped with a highly-modified 200R4, 4 speed Automatic-overdrive transmission an custom lockup torque converter, all specially calibrated with performance-optimized shift points, and strengthened internals. This power was then transfered via a RPO JG1 aluminum driveshaft, with hardened Spicer u-joints and a Spicer yoke, out to a 9-bolt 3.27 limited-slip Borg-Warner rear axle. The entire combination was capable of quarter times in the mid 13's in bone stock trim.

 

[Jan Larsson]

There's a number of errors in that information you find on-line ...

Chevy or Olds 307 V-8 powerplant - doubt this as no-one ever mentioned this not even Bill Owen that was asked to help with the engine from day one.

hydraulic roller camshaft - didnt happen most likely due to cost as they had no budget to develop anything like that

turbocharger w/ a ceramic-impeller - this was the GNX right ... very expensive ... they could use the GNX intercooler as it was no more than the regular GN one and proved to give a few more hp

RPO JG1 aluminum driveshaft - not the case ... and for the hardened spicer U-joints I'm not sure about that unless it was standard for all F-bodies

 

[Jicaju]

Hello,

Does anyone know what the typical combustion chamber volume is on Turbo Trans Am cylinder heads?

Also, are the exhaust port gaskets the same between the Turbo Trans Am and Grand National cylinder heads?

Thank you for any help,
Paul Lohr

My heads were 41 cc's. The exhaust gaskets are different.

Michael

 

[Jicaju]

Here is some technical info on the TTA that should answer your questions. Also, the exhaust port gaskets are unique to the TTA as the heads are. I just rebuilt one and these are the only gaskets that I could find for them, but work perfectly. Hope the info helps.

Remflex RF13-012 header gaskets

http://www.turbotransam.com/forums/showthread.php?t=4956&page=4


Pontiac contracted the TTA engine with Jeff Beitzel and his PAS Engineering in Van Nuys, California, and the work took place in its 40,000-square-foot City of Industry facility. Once completed, the engines were shipped back to GM, installed in the cars, and then returned to PAS for a brief period of testing and quality-control checks before they were offered to the public for sale. Jeff Beitzel, who was the president of PAS, had his personal 20th Anniversary TTA (one of the 1,555) sent to ASC and made into a convertible. Today it's rumored to be owned by a private collector. Only 1,554, were built, Pontiac created the F-body supercar based upon the GNX engine program. Initially, Pontiac engineers wanted to use an all-aluminum Chevy or Olds 307 V-8 powerplant in the TTA. That plan never came to fruition, so the RPO LC2 3.8L Intercooled Buick Turbo V-6 engine was chosen. The 1989 Turbo Trans Am's utilized a 3.800 in. x 3.400 bore, Buick 231ci/ 3.8L "25526109" engine block, w/ "SG1" cast into the side. A nodular-iron crank, with 4 cross-drilled main bearings, fillet mains and rod journals, plus 6 counterweights PN: 25511229. A set of cast Armasteel 151mm-long cast rods, and special design hypereutectic pistons designed to work at 46.4mm of total compression height to produce a compression ratio of 8.0:1. It was fitted with cylinder heads from the existing traverse V-6 3800 Series I heads, PN: 25536702, which yielded superior combustion chamber design & exhaust flow of the GN/GNX design. It allowed room for the downpipe to fit, and also gave more clearance around the strut towers & A/C box on the firewall. It used a hydraulic roller camshaft, with 192/196-degrees duration at .050, .409/.434 lift, 1.71 intake valves and 1.49-inch exhaust valves, with special 1.65:1 rockers. A crank trigger ignition was used to fire the spark plugs more effectively. The spark plug wires of the TTA are unique, embossed with the 20th Anniversary logo, they have plug shields on their ends to prevent burning. A specialized Garrett T-3 turbocharger w/ a ceramic-impeller, provided a maximum of 16.5 psi boost, fed through a GNX-based 12-fin intercooler to a "CERMATEL" (Ceramic/Aluminum) coated pipe to a 75.5mm MAF, 58mm throttle body, and then forced into an aluminum intake manifold. 91 or greater Octane was mandatory to feed the beast's thrist and protect against detonation. Inside the fuel tank, a baffle surrounds the fuel pump and ensured a steady supply of fuel to the pump during sharp turns, specifically designed for the IMSA (International Motor Sports Association) "Showroom Stock" competition. A high volume electric fuel pump was used to feed fuel to a high-pressure Bosch 237 fuel pressure regulator, and metered out to 6 Bosch 28 lb/hr injectors. A specially recalibrated ECM and custom PROM operated the computer system and maintained the balance effectively. Although there are substantial differences between a stock Turbo TA chip and a stock Grand National chip, the ECMs are identical. The spent gasses were expelled via TTA-specific Stainless steel 3-into-1 headers, down into a high flow catalytic converter, and passed though a 2.5-inch exhaust system with a crossflow muffler, and out through dual, polished stainless steel "splitter" tailpipe extensions, similar in style to those used on the Trans Ams of the late 70's. The engine was seriously underrated at 250 hp. In actuality, the TTA motor reportedly made 301 hp on the PAS engine dyno and 10 to 15 lb-ft higher torque than the advertised 340 lb-ft. Chassis-dyno test results of bone stock cars, yield numbers that correspond with TTAs typically making around 220 HP to the rear wheels. A mid-year change was made to the Turbo TA's plastic turbo inlet tube, and replaced with a durable unit with a clamping rib on either end to keep the hoses attached more securely. (A note to assist in saving your stock one from collapse: cut a short 1" length of 3" dia exhaust pipe and insert it into the end of the inlet tube. It's a perfect fit and will allow tighter clamping forces to be applied) The engine also utilized a horizontally-mounted A/C PF-1218 oil filter with an anti-drainback valve to prevent oil starvation at engine startup. The original TTA's serpentine belt was slightly longer than optimal and was a common malady on stock trim car as the belt stretched with use, heat, and age. All Turbo T/A's came equipped with a highly-modified 200R4, 4 speed Automatic-overdrive transmission an custom lockup torque converter, all specially calibrated with performance-optimized shift points, and strengthened internals. This power was then transfered via a RPO JG1 aluminum driveshaft, with hardened Spicer u-joints and a Spicer yoke, out to a 9-bolt 3.27 limited-slip Borg-Warner rear axle. The entire combination was capable of quarter times in the mid 13's in bone stock trim.

SG-1 block is not a cross drilled 4 boltmain block, TTA came with flat tappet cam, TTA did not have a ceramic turbo cahrger impeller, TTA intercooler is different from GNX it has 2 or 3 less rows of fins I know because Richard Clark and I have compared the two before. TTA heads will not flow more than the stock GN heads we have flowed both at Richaed Clarks and the GN heads would low slightly more.



Michael

 

[kman71]

Thanks Jan,

I didn't mean to steer him wrong. As you know, I am just learning this with the recent rebuild, thought maybe the info he was looking for was in some of my research.

I do know for a fact about the gaskets though as I bought the felpro from rock auto that said they were for the TTA and they were not right, the mounting holes did not line up. There may be more that do work, but the one from Remflex is the exact fit and confirmed by me in my rebuild and others on our turbotransam.com site that have used them.

Kris

 

[kman71]

Here is a link to the full article.... sorry about the misinformation. I thought everything posted on the internet had to be true....LOL
I thought it had a lot of great info and was a very interesting read. You can tell the author is enamored with the TTA as we all are, it is great that we have had so much good communication with Scott Kelly and Bill Owen, and Jan and others to investigate to put a real history to our cars, and very grateful for it... I know I am.

http://www.necamaro-firebird.org/forums/viewtopic.php?f=39&t=5459

 

[Jan Larsson]

Here is a link to the full article.... sorry about the misinformation. I thought everything posted on the internet had to be true....LOL
I thought it had a lot of great info and was a very interesting read. You can tell the author is enamored with the TTA as we all are, it is great that we have had so much good communication with Scott Kelly and Bill Owen, and Jan and others to investigate to put a real history to our cars, and very grateful for it... I know I am.

http://www.necamaro-firebird.org/forums/viewtopic.php?f=39&t=5459

You're forgiven Kris

Lots of inaccurate info all over the place ... mostly as they (GM) kept all the information out of the media ... but at least we learn more and more every year and most of it is now out in the open finaly !

 

[Jan Larsson]

Exhaust gaskets are different as they heads are not the same, the exhaust gaskets on the TTA are for the FWD 3.0 heads so the normal gasket (felpro MS93046) will be the one to use however they did not have a gasket from the factory at all.

 

[Jan Larsson]

SG-1 block is not a cross drilled 4 boltmain block, TTA came with flat tappet cam, TTA did not have a ceramic turbo cahrger impeller, TTA intercooler is different from GNX it has 2 or 3 less rows of fins I know because Richard Clark and I have compared the two before. TTA heads will not flow more than the stock GN heads we have flowed both at Richaed Clarks and the GN heads would low slightly more.



Michael

I think they mean the crank is cross drilled not the block.

Funny with the intercooler, Bill Owen said they could use the GNX intercooler as it cost the same as the GN ... so the TTA should be identical to the GNX intercooler or it would have been identical to the GN one as they did not design a new piece (would have cost money) for the TTA. Never counted the fins on a stock TTA one to compare.

 

[TT/Ameasap]

Kris,
Just correct that info and you have a decent write-up. What ever happened to the Sticky's?

 

[Paul Lohr]

Thanks for all the help, gentlemen. This is great.

Summary:

• Combustion chamber volume is around 41 ccs.
• Exhaust port gaskets on GN and TTA heads are not the same.

 

[frank_ster]

yes the fwd Buick v6 doesn't even use exhaust gaskets . on any of the ones i have seen, just the use of high temp silicone is enough.
the gaskets can be useful if the headers have defects.

 

[TT/Ameasap]

I have a rather large write-up on these heads somewhere.... I will dig to find it.