[GTOGEORGE]

Info about your boosted or nitrous race car! Et’s, MPH, Boost numbers, engine parts etc.!


GTO George

[taff2]

8.90@163mph off the footbrake, factory 389 block with welded valley and mains girdle -dry decked,reverse cooled ,3/4 filled and bored to 4.090", AP Scat forged 4.00" crank, Brooks B2 ali rods, BRC forged ali pistons, 7.25-1 compression, Comp custom turbo cam -flat tappet with around 250* @.050", .625" lift with 1.65 Scorpion rockers and .875" lifters, Siamesed home ported factory 96 heads, modded Offy 360 dual carb intake with two 600 double pumpers, 1 5/8" ID headers into twin Master Power T70 turbos, water/meth chemical intercooling, 18 psi boost on a very soft tune using pump fuel and octane booster.
New combo -I've switched to Ross forged pistons in a 4.125" bore with 10.5 compression ratio, slightly more duration and less lift Comp flat tappet cam, Holley HP efi with dual 75mm throttle bodies, 220lb injectors, CNP ignition, 25 psi boost, can't go much above this as I have a 7.50 chassis tag!

[GTOGEORGE]

Originally Posted by taff2

8.90@163mph off the footbrake, factory 389 block with welded valley and mains girdle -dry decked,reverse cooled ,3/4 filled and bored to 4.090", AP Scat forged 4.00" crank, Brooks B2 ali rods, BRC forged ali pistons, 7.25-1 compression, Comp custom turbo cam -flat tappet with around 250* @.050", .625" lift with 1.65 Scorpion rockers and .875" lifters, Siamesed home ported factory 96 heads, modded Offy 360 dual carb intake with two 600 double pumpers, 1 5/8" ID headers into twin Master Power T70 turbos, water/meth chemical intercooling, 18 psi boost on a very soft tune using pump fuel and octane booster.
New combo -I've switched to Ross forged pistons in a 4.125" bore with 10.5 compression ratio, slightly more duration and less lift Comp flat tappet cam, Holley HP efi with dual 75mm throttle bodies, 220lb injectors, CNP ignition, 25 psi boost, can't go much above this as I have a 7.50 chassis tag!

That’s what I’m talking about! Thanks!

GTO George

[GTOGEORGE]

Originally Posted by taff2

8.90@163mph off the footbrake, factory 389 block with welded valley and mains girdle -dry decked,reverse cooled ,3/4 filled and bored to 4.090", AP Scat forged 4.00" crank, Brooks B2 ali rods, BRC forged ali pistons, 7.25-1 compression, Comp custom turbo cam -flat tappet with around 250* @.050", .625" lift with 1.65 Scorpion rockers and .875" lifters, Siamesed home ported factory 96 heads, modded Offy 360 dual carb intake with two 600 double pumpers, 1 5/8" ID headers into twin Master Power T70 turbos, water/meth chemical intercooling, 18 psi boost on a very soft tune using pump fuel and octane booster.
New combo -I've switched to Ross forged pistons in a 4.125" bore with 10.5 compression ratio, slightly more duration and less lift Comp flat tappet cam, Holley HP efi with dual 75mm throttle bodies, 220lb injectors, CNP ignition, 25 psi boost, can't go much above this as I have a 7.50 chassis tag!

I have the same problem, my car will only cert to 7.50 but lucky for me or my cars chassis I can only get 11 lbs of boost from my smallish 8-71!


GTO George

[Jack Gifford]

An "oddity" of the blown 4 cylinder (DOHC hemi) that I'm presently fitting into the lakester- it uses a billet TBS 14-71, which is almost three times the displacement of the engine!

I want to test whether "big blower turning slowly" might heat the intake charge less than "little blower turning fast".

My prior Roots-blown experience was all with a "little" blower (small rotor 6-71, 353 c.i.) overdriven on various Pontiac engines of around 400 c.i. At 8-9,000 RPM I saw plenty of mixture heating.

[twooldgoats]

My blown Pontiac info is in my signature (current bests) and in this 21-page thread that covers in excruciating detail converting my car from an 8-second NA car to a 7-second blown alky car:


http://forums.maxperformanceinc.com/...d.php?t=711959


I still run the car a few times a year and hope to improve my best time and speed later this year at the Pontiac Heaven race in Phoenix (November 1-3, 2019).



Incidentally, I believe strongly that mechanical fuel injection is the only way to go in a blown alky drag-race application.


Jim

[GTOGEORGE]

Originally Posted by Jack Gifford

An "oddity" of the blown 4 cylinder (DOHC hemi) that I'm presently fitting into the lakester- it uses a billet TBS 14-71, which is almost three times the displacement of the engine!

I want to test whether "big blower turning slowly" might heat the intake charge less than "little blower turning fast".

My prior Roots-blown experience was all with a "little" blower (small rotor 6-71, 353 c.i.) overdriven on various Pontiac engines of around 400 c.i. At 8-9,000 RPM I saw plenty of mixture heating.

Jack have you looked into a Hampton 8-71 2 lobe blower they are suppose to pass the same air as a 14-71 but in the same size as a 8-71 (best of both worlds)!


GTO George

[GTOGEORGE]

My set up......MR-1 block with HP heads (2.25 & 1.75 valves with T & D rocker shaft system), Ross pistons 111035 4.31b dish, Total Seal gapless piston rings, GRP aluminum rods 6.70" (5500 series Pro Mod), cam specs are 272 intake......288 exhaust........440 lobe lift with 110 lobe separation. (not a perfect cam but it seems to work). I have a Mellings oil pump with 70 psi, Crankshaft is a Modex Billet (gun drilled) with 4.50" stroke and 3" mains with 2.20" rods. i run a double o-ring set up (one o-ring made into the copper gasket and the other in the block). I run a dry deck just incase my cylinder head starts lifting...and they do. Also have 1/2" ARP head studs. My timing is at 27- 28 degrees.....back in the old days with my B & M blower with steel heads I ran 34 degrees all the time (no problems) thats was with around 6-8 lbs of boost. I know that Jim runs around 30 degrees timing with his 15 plus funds of boost. Yes jim Mech fuel injection is the way to go BUT I stuck with my 1050 Holleys with a Alcohol conversion kit with 204 jets! I have an electric Magnafuel 500 fuel pump with 2 fuel cells a 3 gal in front which i pull from and a 5 gal in back when I need more fuel (driving to and from the 1/4 mile)......its a Bracket Car! Also a smallish 8-71 3 lobe BDS Roots blower. I have double adjustable Strange shocks in the back and a Team Z motorsports Anti-roll bar. I have a HI-7 Crane ignition box with a Crane DES90000 control box and a Crane Fireball coil. I use a Computech Data Recorder with their LCD screen display. Lets not forget the Dana 60 rear end with Strange 35 spline axles and spool and the Spicer 3.73 street gears.
Id like to thank KRE and Don from DCI for all their HELP and also Team Z Motorsports for all their Chassis work!

GTO George

[Scott Roberts]

Originally Posted by GTOGEORGE

I have the same problem, my car will only cert to 7.50 but lucky for me or my cars chassis I can only get 11 lbs of boost from my smallish 8-71!


GTO George

That is all you can get? What kind of timing are you running George?

[GTOGEORGE]

Originally Posted by Scott Roberts

That is all you can get? What kind of timing are you running George?

27 degrees with 27over.

GTO George

[GTOGEORGE]

Tommy Youman is tearing up the dragstrip with his WARP 6 twin turbo 1970 GTO it goes to show you what a Pontiac can do with a set of GREAT flowing heads and twin Turbos..........its rumored to have the MOST HP of any Pontiac to date..........over 3,000 hp to the rear wheels, thats around 3,500 flywheel HP! Heads do matter, DONT Let people fool you!!


GTO George

[GTOGEORGE]

Remember you can make HP with stock type heads with a boosted device BUT to make BIG HP a better set of heads are needed!

GTO George

[68azbird]

Originally Posted by GTOGEORGE

Remember you can make HP with stock type heads with a boosted device BUT to make BIG HP lots more $$$ and your first born Is needed!

GTO George

Fixed it

[GTOGEORGE]

Originally Posted by 68azbird

Fixed it

That’s a fact!



GTO George

[taff2]

My first born is building his own race car now, so he'd better get married and get a kid of his own.

[Scott Roberts]

Originally Posted by GTOGEORGE

27 degrees with 27over.

GTO George

Put more timing in it and wala....7 sec 1/4.. I have gone as high as 40 deg on a blown engine... but I was running for max power and didn't care about reliability....

[twooldgoats]

Originally Posted by Scott Roberts

Put more timing in it and wala....7 sec 1/4.. I have gone as high as 40 deg on a blown engine... but I was running for max power and didn't care about reliability....

I have always run 32 deg on mine with no issues. Haven't taken any out, though I could.


Jim

[GTOGEORGE]

Originally Posted by twooldgoats

I have always run 32 deg on mine with no issues. Haven't taken any out, though I could.


Jim

I plan on bumping it up to 28 next time out but I doubt I’ll go any higher.

GTO George

[taff2]

Take a look at the timing mark on the plugs earth straps,this will point you in the right direction. Not the same engine I know-but we used to run 32-34 degrees on a 6V-71 blown BBC at around 12 psi , and this was safe. Every 2 degrees extra we put in gave us 50hp more according to the time slips.

[RAIV-Z]

At 10lb boost, I'm at 30 degrees currently. 9.1:1 compression.