408 LTx build finally hit the rollers
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TECH Junkie
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Joined: Nov 2001
Posts: 3,944
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From: Glen Burnie, Md
408 LTx build finally hit the rollers Been a long term project, trying to get a LTx to run with whats considered normal and available off the shelf for the LSx guys. 408 (Thanks to Erik @ HKE) 11.3:1, hyd roller, cylinder head that goes over 300 cfm, things that are average for LS guys, but LT guys lack - moderately price 400 inch engines, intake manifolds with some runner length, decent cylinder heads.
With some help from the guys at TEA, especially Brian Tooley, got a decent set of heads to help feed a motor this big. Pretty much everything off the shelf weve ever dealt with for the LT1 stuff is small for a 383 or even 350 inch engine much less something like this - but results look like they are feeding it pretty well.
The LS engines always kill the non existant runner length LTx stuff in the midrange, but we planned from jump street to modify/use the Edelbrock Pro Flow manifold to get the runner length something a little more reasonable with a engine spending most its time from 3000-7000. Had to spend some time with the intake flange to get the LSx 95mm TB packaged as tightly as possible, but it all came out a good fit, from some rough measurements I took looks like it could fit under some of the aftermarket Fbody hoods.
With a set of 1 3/4" headers (1 7/8 were planned but had some delays with the making of a custom set) full dress (AC, power steering, Alt etc) thru the Vig converter flashing to 5200, 3.73 gears in 8.5" rear, made 466 hp and 399 lb ft. Roughly 20 more than a 408 LS1 combination that went 10.3 NA at @3700 lbs
Funny thing is the setup is sitting in something about as non descript as possible, old 9C1 Caprice cop car, black steelies all the way around... only thing is the back ones are widened to 12" with 325 Mickey Thompsen radials on them. Someones feelings might end up getting hurt
With some help from the guys at TEA, especially Brian Tooley, got a decent set of heads to help feed a motor this big. Pretty much everything off the shelf weve ever dealt with for the LT1 stuff is small for a 383 or even 350 inch engine much less something like this - but results look like they are feeding it pretty well.
The LS engines always kill the non existant runner length LTx stuff in the midrange, but we planned from jump street to modify/use the Edelbrock Pro Flow manifold to get the runner length something a little more reasonable with a engine spending most its time from 3000-7000. Had to spend some time with the intake flange to get the LSx 95mm TB packaged as tightly as possible, but it all came out a good fit, from some rough measurements I took looks like it could fit under some of the aftermarket Fbody hoods.
With a set of 1 3/4" headers (1 7/8 were planned but had some delays with the making of a custom set) full dress (AC, power steering, Alt etc) thru the Vig converter flashing to 5200, 3.73 gears in 8.5" rear, made 466 hp and 399 lb ft. Roughly 20 more than a 408 LS1 combination that went 10.3 NA at @3700 lbs
Funny thing is the setup is sitting in something about as non descript as possible, old 9C1 Caprice cop car, black steelies all the way around... only thing is the back ones are widened to 12" with 325 Mickey Thompsen radials on them. Someones feelings might end up getting hurt
Killer numbers through a power-robbing drivetrain. That car is going to break some hearts for sure. Great sounding combo. 
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
pics of 12" wide steelies???
Thread Starter
TECH Junkie
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From: Glen Burnie, Md
This thing has countless hours in it, I dont even want to start adding them up, but here are some of the things I thought to take pictures of, most of them I was to aggrevated about to stop and take pictures of while coming up with a solution We will just act like all the other problems I ran into trying to button this thing never happend, but here is a small sample
Std LT1 plugs protrude WAY into the chamber on this casting/CNC program. Finding the right, no just any .440" reach plug took some time to dig up around here
To get the port alignment correct 4 intake gaskets later, had to build the Great Wall of China for the china wall, no biggie
Pushrod pinch is about tapped, ran everything about as tight as you can get it, no one offered any rocker sets with the needed offsets, so we figured out what rocker bodies/offsets were needed after many fitments of existing part numbers, had a new part number created, waiting for the slow boat from Australia to arrive was rough but after a couple months the rocker side of things was handled. Cleared the ports by a hair, even fitting 3/8" pushrods (all of this would be much easier with offset solid lifters but nothing like that for hyd valvetrains) AND fit under the OEM valve covers with some slight clearencing.
Even had to go so far as to modify the head gaskets to fit the chambers/block perfect
We will just act like all the other problems I ran into trying to button this thing never happend, but here is a small sampleStd LT1 plugs protrude WAY into the chamber on this casting/CNC program. Finding the right, no just any .440" reach plug took some time to dig up around here
To get the port alignment correct 4 intake gaskets later, had to build the Great Wall of China for the china wall, no biggie
Pushrod pinch is about tapped, ran everything about as tight as you can get it, no one offered any rocker sets with the needed offsets, so we figured out what rocker bodies/offsets were needed after many fitments of existing part numbers, had a new part number created, waiting for the slow boat from Australia to arrive was rough but after a couple months the rocker side of things was handled. Cleared the ports by a hair, even fitting 3/8" pushrods (all of this would be much easier with offset solid lifters but nothing like that for hyd valvetrains) AND fit under the OEM valve covers with some slight clearencing.
Even had to go so far as to modify the head gaskets to fit the chambers/block perfect
Last edited by GrannySShifting; Sep 20, 2010 at 02:58 PM.
Thread Starter
TECH Junkie
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Joined: Nov 2001
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From: Glen Burnie, Md
Even had to do some clearancing on the exterior of the castings to get stuff to bolt together. One of those examples where parts work fine sitting on the bench by themselves but dont want to play well with all the other parts once they are in the sandbox together.
Middle picture is one of dozens of mockup runs, Ive bolted and unbolted more pairs of cylinder heads on this thing before it even fired, than I have on cars that have ran for years. Can see the land yacht sitting on deck in the background.
Last two is of a few MORE parts that done work well with others once they are all in the same sandbox. See if anyone can pick out the problem you run into with this timing gear running on these motors.
Middle picture is one of dozens of mockup runs, Ive bolted and unbolted more pairs of cylinder heads on this thing before it even fired, than I have on cars that have ran for years. Can see the land yacht sitting on deck in the background.
Last two is of a few MORE parts that done work well with others once they are all in the same sandbox. See if anyone can pick out the problem you run into with this timing gear running on these motors.
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Badass, you should take it to a happy dynojet just for grins
We worked out the correct spark plugs before they shipped
At least the heads had SBC intake bolt holes like you requested
We worked out the correct spark plugs before they shipped
At least the heads had SBC intake bolt holes like you requested
Thread Starter
TECH Junkie
iTrader: (10)
Joined: Nov 2001
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From: Glen Burnie, Md
Problem was when you used std reach plugs washered out to correct depth in chamber, the porcelain/tip was too tight to the header primaries to get plug wire boots on, much less not melt. Just another one of the works well alone, doesnt play well with others things we ran into. Wasnt for lack of trying on your part Brian!
Yessir, Mr Tooley whipped us up a LTx reverse cooled casting with a SBC CNC port/chamber and intake man flange that did the job, on our local bench they were right with LS1 AFR 225s up to .600 lift or so. Did a halfway decent job of it too
I was real disappointed not to be able to get my junk pile back together for the Bowling Green race and try and catch up with you, but if it can go wrong, well you know
jeff the explanation of countless hours isnt even the right term for this project, you started this thing a few years ago and now its getting near completion. And I know mike is probably very happy with it considering how much fabrication really had to go into it, it seemed like just about everything had to be modified to make it work.
I cant agree with that statement, it always seemed like one problem after the next when you were fitting everything. Even the motor gave you **** going together along with the optispark but thats a giving with the optispark.
Teching In
Joined: Dec 2006
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How about one of Jeff,since he was so nice to post that pic of me having a heart attack looking at the pre-China Wall gap:
And here's a link to one of the first dyno runs before Jeff got serious with the tuning last sat.:
http://www.youtube.com/watch?v=YgO4coYbUzU
And here's a link to one of the first dyno runs before Jeff got serious with the tuning last sat.:
http://www.youtube.com/watch?v=YgO4coYbUzU
Last edited by SStomp66; Sep 23, 2010 at 10:12 PM.
Thread Starter
TECH Junkie
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From: Glen Burnie, Md
Its a TFS 230cc casting, peaks at 6700. CYlinder head is feeding this big of a motor, itll be good and plenty on the run of the mill 350/383 stuff. When I started the gears turning number one priority was get a real cylinder head on it for a change vs the regular LTx stuff. I think we accomplished that.
LS1 TB was for packaging reasons under hood and it fits the intake better. Intake was designed to use a LS TB but not quite factory bolt pattern, two were off, since we flipped it upside down anyway made new bolt pattern/flange/throttle cable arrangement