421 Stroker Questions
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Intermediate
Joined: May 2011
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421 Stroker Questions
I finally bought my first Corvette this month, a beatiful 89 z51 coupe.
The previous owner intended to put a 421 stroker in it. A quick google search found this:
http://www.skipwhiteperformance.com/...=421%20STG%204
in case you don't follow links it's a bowtie block, scat forged internals, with dart platinum pro 1 heads for less than $7k.
My questions are:
Cam: it has a hydraulic roller cam, with about .575 lift. How radical is that? I do most of my driving on the street, I don't want a car that's a real pain in traffic. Is that cam truly street friendly? I could get a milder cam and just spray it if I want to go really fast.
Driveline: what's going to have to be changed behind that engine (it's about 600 hp and 550+torque) and what can be kept stock?
Exhaust: will those L98 headers fit those Dart Pro 1 heads?
I already figured on swapping the radiator, and intend to equip it with a mini-ram. After that I suppose I'll need bigger tires... but a car should always be "traction limited" IMHO.
The previous owner intended to put a 421 stroker in it. A quick google search found this:
http://www.skipwhiteperformance.com/...=421%20STG%204
in case you don't follow links it's a bowtie block, scat forged internals, with dart platinum pro 1 heads for less than $7k.
My questions are:
Cam: it has a hydraulic roller cam, with about .575 lift. How radical is that? I do most of my driving on the street, I don't want a car that's a real pain in traffic. Is that cam truly street friendly? I could get a milder cam and just spray it if I want to go really fast.
Driveline: what's going to have to be changed behind that engine (it's about 600 hp and 550+torque) and what can be kept stock?
Exhaust: will those L98 headers fit those Dart Pro 1 heads?
I already figured on swapping the radiator, and intend to equip it with a mini-ram. After that I suppose I'll need bigger tires... but a car should always be "traction limited" IMHO.
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
Not enough cam specs to tell what it is and if its an EFI friendly cam
You carbing it or stickign with EFI? Youll need a decent size header on it too.
tpi421Vette here on the forum does a LOT of 421s maybe he will pipe in.
You carbing it or stickign with EFI? Youll need a decent size header on it too.
tpi421Vette here on the forum does a LOT of 421s maybe he will pipe in.
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Joined: May 2011
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I've already got Melrose long tube headers and full 3" exhaust. I'd much rather run a mini ram efi than a carb.
Thread Starter
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Thread Starter
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So, assuming similar duration and lobe seperation angle, how much difference will that extra .020" lift make? All I'm really concerned about is that the engine doesn't stall easily or run like crap from idle to 2000RPM, because that's about the engine speeds I'll be seeing on the street. I'm pretty sure they'll put a milder cam for the same price, but it may cost 50-75 HP. That's ok with me, because a bottle would fix that easily. I'm only gonna want to go that fast on a track anyhow.
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From: Indianapolis IN
There is soooo much more too it than cam numbers, what are your goals, max ET, max 1/4 MPH,,, what is the static CR / Dynamic CR,,, what rear gears,,,, auto or stick . stall? ,,,,, the Miniram does not help at low RPM and with 230cc heads, you will need gears @ 3.5x or higher IMO,,, ,, but nothing happens at idle to 2000 rpm anyway IMO, even during street driving, I shift higher than 2000 rpm
I will step aside and let some others chime in, Rick should be along soon, he has a 421
I will step aside and let some others chime in, Rick should be along soon, he has a 421
Thread Starter
Intermediate
Joined: May 2011
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There is soooo much more too it than cam numbers, what are your goals, max ET, max 1/4 MPH,,, what is the static CR / Dynamic CR,,, what rear gears,,,, auto or stick . stall? ,,,,, the Miniram does not help at low RPM and with 230cc heads, you will need gears @ 3.5x or higher IMO,,, ,, but nothing happens at idle to 2000 rpm anyway IMO, even during street driving, I shift higher than 2000 rpm
I will step aside and let some others chime in, Rick should be along soon, he has a 421
I will step aside and let some others chime in, Rick should be along soon, he has a 421
Like I said, it's only in the planning stages but I will have the time and money this winter. I'm just trying to make sure it's what I really want and also make sure I have enough money to complete the project before I get started. A disassembled 'Vette isn't any fun at all.
The previous owner made a lot of nice mods to the car, it's already a blast to drive but I'm already craving more power.
Probably shouldn't have read all those Hot Rod mags as a kid, lol.
Team Owner
Joined: Oct 2004
Posts: 81,242
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From: altered state
St. Jude Donor '05
Jim will set you straight.
As said lift hardly has anything at all to do with idle or low end much much much more to it than that. 421 is a big motor and can handle plenty of cam and still make tons of low end. With your 3.73 I wouldnt worry about a thing you could put about any cam and it would still move hard off the line. You got a stick so you can slip the clutch to any rpm you want anyway.
As said lift hardly has anything at all to do with idle or low end much much much more to it than that. 421 is a big motor and can handle plenty of cam and still make tons of low end. With your 3.73 I wouldnt worry about a thing you could put about any cam and it would still move hard off the line. You got a stick so you can slip the clutch to any rpm you want anyway.
Team Owner
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From: Athens AL
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Yeah the website only say's that it's a Howards hydraulic roller cam .568/.574 lift. Nothing about duration or lobe seperation angles. I don't mind a nice lopey idle as long as it isn't very difficult to drive in slow downtown traffic.
I've already got Melrose long tube headers and full 3" exhaust. I'd much rather run a mini ram efi than a carb.
I've already got Melrose long tube headers and full 3" exhaust. I'd much rather run a mini ram efi than a carb.
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I was wondering if I'll need a new clutch, tranny upgrade, or driveshaft/diff/halfshafts?
Do you still have the FAST ECM? That one fella kept saying the stock ECM can handle the 421, others said not.
Like I said, I'm just trying to figure out how much this will cost, the engine is $7 k and seems to be a great deal.
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I'm trying to get an idea of the total cost involved with intake and drivetrain upgrades. So, I need to know what breaks at 600hp.
I plan to use the car for HPDEs, autocross, and an occasional drag strip pass.
Pro
Joined: Mar 2004
Posts: 508
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From: N.W. CT
I started a project similar to this over a year and a half ago. So far everyone that has replied to your thread is very knowledgeable and each one of them has helped and still help me with my setup.
Save at least 30-40% more money than you plan on spending this winter. I noticed my funds ran low fast. The little stuff adds up quick. You should upgrade your clutch, u-joints,fuel system, etc, etc.
I sent my trans to Bill at zfdoc. He is the only one that I would trust with it.
For some reason I keep checking off my list of things to do and it keeps getting bigger
. Good luck with the build.
Save at least 30-40% more money than you plan on spending this winter. I noticed my funds ran low fast. The little stuff adds up quick. You should upgrade your clutch, u-joints,fuel system, etc, etc.
I sent my trans to Bill at zfdoc. He is the only one that I would trust with it.
For some reason I keep checking off my list of things to do and it keeps getting bigger
. Good luck with the build.
Last edited by Doughboy2k3; May 27, 2011 at 05:16 PM. Reason: trans
Thread Starter
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Thanks. Like I said I'm trying to make sure I can finish the project before getting started. A disassembled Vette ain't that much fun.
What I'm most confused about is what engine management system I'll have to use. Anybody here running a 421 with the stock ECM ? Who can I get to reprogram mine?
What I'm most confused about is what engine management system I'll have to use. Anybody here running a 421 with the stock ECM ? Who can I get to reprogram mine?