447 stroker on the way!
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From: Lawrenceburg Ky
447 stroker on the way! Well 2 weeks ago I had a catastrophic failure with my 421 (4.030 bore x 4.125 stroke) at the track. Over the winter I had a local shop swap the heads out for some Tony Mamo AFR Mongoose LS3 heads and a FTI powerglide. I've been shifting at 7000 and running upper 10.20's with no problems but decided to try 7200 and see if it would pickup, when a valve kissed a piston. The heads are destroyed, 1 piston is trashed, 1 bent rod, block is cracked, the cam is good. I spent so much over the winter that I'm now on a somewhat limited budget to get racing again. The shop that did the work won't respond to me at all.....grrrrr. So I decided to get the best/biggest shortblock I can afford,thus I ordered a 447 (4.155 bore x 4.125 stroke in a sleeved Gen iv block) from Texas Speed but then I will have to make due with what I have on hand for the rest of it, I have a set of CNC 821 heads from Katech Engineering, stock rockers with Straub bushings, 11/32 pushrods that are .120 wall, LS7 lifters, and I will reuse my hydraulic roller cam which is .623/.623 lift, 247/261 duration, 113 + 4 lobe sep, and also have a new LOD Speedworks intake that was ordered prior to the engine failure. Obviously I would like to get a nicer set of heads, and a LLSR setup but it's simply not in the budget at this time (maybe next year). My question to you guys is: I think I can break well into the 9's with this big engine that has a mild top end, what do you think? I would also like to thank Dan Miller (aka NAVYBLUE210) for his messages and phone calls of support and advice.....you're a great guy and it's much appreciated!
Last edited by BigDaddy97; Jul 6, 2019 at 04:54 PM.
Your new motor should get nines. Expect about the same power as the 421 but higher torque with smoother curve.
Surprised a 454 was not the same basic price at 4.185x4.125
Surprised a 454 was not the same basic price at 4.185x4.125
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Which is why i spent couple xtra bucks on an RHS block over a factory ls7 for my build...it would have been different if i already owned an ls7, but i didnt. In hindsight (now that i sold my ls2 6.0l), i should have kept that and sent it out to get the 468ci treatment or something similiar. At the time i started my RHS build, i thought i was gunna be saving the ls2 for a turbo gbody build. Those plans quickly fell thru.
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My best pass on the old 421 iron block was 10.26. The new aluminum block saves 100 pounds which is worth an extra 1/10th in the quarter, and I'm thinking the extra cubes will push me the rest of the way into the 9's.We shall see 
Last edited by BigDaddy97; Jul 7, 2019 at 09:02 AM.
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How much does your S10 weigh ?
If your 421 was making 1.6 hp per cube equals 675 horsepower.
Multiply 447 by 1.6 hp per cube and you get 716 horsepower.
Both motors should make the same/pretty close horsepower per cube if using the same heads, headers, intake, cam etc
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What is your weight? i have a s10 and 408. :....1st combo was good for a 9 depending on power level.
700+ and 3000 lbs for 9's as a basic reference # and good set up.
10's is not a option.
414 lq4 = 756hp @ 7560 that's using FED factory ls3 heads and 11.8 compression. It's how you look @ the glass? Half full or ...
Compression makes 4 a great friend. My thought was FED comp @ 11.8 & similar cam. Now with milling and flycutting we're looking at 13.2 e85 dependant + hp
Guy's build bigger Yet generally the smaller one works just as well. Or just spending $$$$$
700+ and 3000 lbs for 9's as a basic reference # and good set up.
10's is not a option.
414 lq4 = 756hp @ 7560 that's using FED factory ls3 heads and 11.8 compression. It's how you look @ the glass? Half full or ...
Compression makes 4 a great friend. My thought was FED comp @ 11.8 & similar cam. Now with milling and flycutting we're looking at 13.2 e85 dependant + hp
Guy's build bigger Yet generally the smaller one works just as well. Or just spending $$$$$
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421 had a 9 easy. Super vic 4500 and a decent solid roller to about 7300... tq is hp. Best wishes on your new thought.
My builder said he's gave me a lil extra room besides typical race tolerance for P to V clearances with flycutting. As this my interpretation of a street engine ver.1 another head package awaits.
-5cc flat top piston( valve pockets for ls 3&7 heads) 62cc milled FED ls3 stg1 heads with 735 inches of lift. Zach said he can get the valves to clean the pistons of carbon..lol.
My builder said he's gave me a lil extra room besides typical race tolerance for P to V clearances with flycutting. As this my interpretation of a street engine ver.1 another head package awaits.
-5cc flat top piston( valve pockets for ls 3&7 heads) 62cc milled FED ls3 stg1 heads with 735 inches of lift. Zach said he can get the valves to clean the pistons of carbon..lol.
Last edited by Smokey B; Jul 7, 2019 at 11:30 AM.
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We do resleeve's also. Dry sleeve as of now. Depending on hp levels & rpm is how a block is to be chosen. Ls3 factory sleeves move around some past 8500 rpm. Ls 7 sleeves crack due 2 pressure added with a few other things high compression and slight overbore, etc....
If the thought is a aluminum block get a Darton re Sleeve factory block and be done. Zach and the crew have the guys shortblk done for boost, that i sold to the guy. Started life as aluminum 5.3 via Tuskey Z now 418 ls3 dry sleeve Boost Friendly.
If the thought is a aluminum block get a Darton re Sleeve factory block and be done. Zach and the crew have the guys shortblk done for boost, that i sold to the guy. Started life as aluminum 5.3 via Tuskey Z now 418 ls3 dry sleeve Boost Friendly.
Last edited by Smokey B; Jul 7, 2019 at 01:06 PM.