421 stroker question vs. LS Swap ~ experts please
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 810
Likes: 58
From: Alva Florida
421 stroker question vs. LS Swap ~ experts please
I have a 1990 C4 with a ZF-6 speed, and 4:10 gears, Stage 3 clutch with a single mass flywheel. TPIS Headers ceramic coated, Corsa Exhaust.
I built a 421 stroker a couple of years ago, and was power hungry. Here's the rough engine specs.
Dart Shp Block
4340 3.875 stroker crank
6.0" Oliver billet rods
Srp forged pistons
Comp Cams 236/245 @.050 duration, 5.70intake .574 exhaust 113 LSA
Dart pro1 230cc cylinder heads
Air Gap RPM intake
Comp Cams magnum 1.5 Roller Rockers
Howards +.030 Bar lifters for the Dart Block
MSD Distributor
FiTech 600 power adder Throttle body EFI self tuning
Here's the question. I sold my C5 last week, and am considering trying to tame the C4 into more of a daily driver type car (it has air conditioning). Should I get some AFR 210cc heads and a 225/235 ish cam as a good streetable setup? I'm going nuts trying to decide on cylinder heads and cam because everyone I ask about it is leaning in hard on it making 600 plus HP (let it rev / breathe...big heads and cam)..I really want it to drive nice. Or is that too much to ask.
I'm also considering an LS Swap, but am not sure if I could figure out what to do with all the wiring....and what to do with the 421 that works terrific except a little rough for a street engine. Plan B could be to just get a C5 Z06.
Any and all suggestions/opinions are welcome.
I built a 421 stroker a couple of years ago, and was power hungry. Here's the rough engine specs.
Dart Shp Block
4340 3.875 stroker crank
6.0" Oliver billet rods
Srp forged pistons
Comp Cams 236/245 @.050 duration, 5.70intake .574 exhaust 113 LSA
Dart pro1 230cc cylinder heads
Air Gap RPM intake
Comp Cams magnum 1.5 Roller Rockers
Howards +.030 Bar lifters for the Dart Block
MSD Distributor
FiTech 600 power adder Throttle body EFI self tuning
Here's the question. I sold my C5 last week, and am considering trying to tame the C4 into more of a daily driver type car (it has air conditioning). Should I get some AFR 210cc heads and a 225/235 ish cam as a good streetable setup? I'm going nuts trying to decide on cylinder heads and cam because everyone I ask about it is leaning in hard on it making 600 plus HP (let it rev / breathe...big heads and cam)..I really want it to drive nice. Or is that too much to ask.
I'm also considering an LS Swap, but am not sure if I could figure out what to do with all the wiring....and what to do with the 421 that works terrific except a little rough for a street engine. Plan B could be to just get a C5 Z06.
Any and all suggestions/opinions are welcome.
Team Owner
Joined: Sep 2001
Posts: 62,153
Likes: 1,731
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
I'd say my 398 is about at the limit of daily street usefulness, my cam is a Crower with about 221/230ish duration @050 and I run AFR 195 heads. It makes 500ish power and torque.
So long as I keep the idle right, it runs just fine on the street. It doesn't like a lot of timing, 30* is about all it wanted. It still gets me 19.4mpg average. If the idle is not set a little higher, it'll die at stoplights, especially so on a cold day, so I tweak it for winter. I actually don't run AC anymore because I still haven't fabbed up a replacement for the rear AC support piece, but if I hooked it up it would work just fine. Those accessory supports are necessary or you start snapping mounting brackets (which is unobtainium right now) when the AC kicks on, or you can rev the motor and torque the brackets.
Other than those caveats, it would handle daily duty just fine if I chose to drive it that often. No C4 blower fan is really high powered to me, so AC never quite keeps up with the worst southern summer heat unless you run it nonstop, so I might recommend adding heat-shielding/sound deadening below the carpet if I were going to drive daily year-round.
So long as I keep the idle right, it runs just fine on the street. It doesn't like a lot of timing, 30* is about all it wanted. It still gets me 19.4mpg average. If the idle is not set a little higher, it'll die at stoplights, especially so on a cold day, so I tweak it for winter. I actually don't run AC anymore because I still haven't fabbed up a replacement for the rear AC support piece, but if I hooked it up it would work just fine. Those accessory supports are necessary or you start snapping mounting brackets (which is unobtainium right now) when the AC kicks on, or you can rev the motor and torque the brackets.
Other than those caveats, it would handle daily duty just fine if I chose to drive it that often. No C4 blower fan is really high powered to me, so AC never quite keeps up with the worst southern summer heat unless you run it nonstop, so I might recommend adding heat-shielding/sound deadening below the carpet if I were going to drive daily year-round.
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
I daily drove a 383 with a 230/236 comp cams 280xfi and It was not what I would call tame but also not ridiculously wild to the point that it was a pain in the *** to drive.
if you are considering swapping to the LS platform just because you think it has better drive ability, I wouldn't do it based on that alone. Is it better? Probably. Not worth all of the hassle for something you want to keep mild imo. The reason for my LS swap is that I want to boost it eventually and the platform is able to do it with a stock block. if I was not going boost down the road I would have just stayed small block Chevy.
I would just find a relatively mild cam matched with a decent set of heads and run the Gen 1 stuff
if you are considering swapping to the LS platform just because you think it has better drive ability, I wouldn't do it based on that alone. Is it better? Probably. Not worth all of the hassle for something you want to keep mild imo. The reason for my LS swap is that I want to boost it eventually and the platform is able to do it with a stock block. if I was not going boost down the road I would have just stayed small block Chevy.
I would just find a relatively mild cam matched with a decent set of heads and run the Gen 1 stuff
Last edited by Pwnage1337; Aug 27, 2019 at 05:56 PM.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
LS swap to make it streetable? Heck no thats the hard way
tpi421vette may be a good guy to talk to re those heads/cam; I dont think youll be happy wiht an LS after having had the torque youre used to.
tpi421vette may be a good guy to talk to re those heads/cam; I dont think youll be happy wiht an LS after having had the torque youre used to.
Last edited by cv67; Aug 27, 2019 at 07:07 PM.
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 810
Likes: 58
From: Alva Florida
398? Sorry, I'm not sure what that is. CI...HP....Torque?
Yes, the C4 electric fan is weak...and I'm here in South Florida. UGH!
Thanks. I really just want to enjoy the car. I have a lot of time, money, and effort in the car.
Thanks,
Justin
Yes, the C4 electric fan is weak...and I'm here in South Florida. UGH!
Thanks. I really just want to enjoy the car. I have a lot of time, money, and effort in the car.
Thanks,
Justin
Team Owner
Joined: Sep 2001
Posts: 62,153
Likes: 1,731
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Well 398 ci yes, I said it has 500ish HP/Tq.
Drifting
Joined: Mar 2018
Posts: 1,362
Likes: 400
From: DFW TX
I think it is a no-brainer to keep what you have and just tame it down a bit. LS swaps are awesome but time consuming and expensive if it isn't a beater/racecar.
Talking about cubes (cuisinartvette already edited his post), I am fairly certain my little 364 cubic inch LS is making 500ish hp/tq and it is quite easy to stroke a LS too.
Talking about cubes (cuisinartvette already edited his post), I am fairly certain my little 364 cubic inch LS is making 500ish hp/tq and it is quite easy to stroke a LS too.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Melting Slicks
Joined: May 2001
Posts: 3,270
Likes: 26
From: Winchester VA
Cruise-In V Veteran
I was in the same boat about 7 yrs ago. Had a 434 with 18 degree heads and Accel DFI. The build went south and I decided to just go tame, given all the engine mgt stuff was gone and other mods for the 18 degree setup, LS was an easy choice for me. I agree with cuisinart, for you, I would not to go LS. There are a couple really good guys here that will give you direction on taming down that motor, may not need smaller heads so like Pacerx said, maybe just a cam swap away from what you want.
Just my opinion, but I think once you've removed the TPI unit, be it an aftermarket intake on an early car or owning an LT based model year, the LS gets a lot less attractive for like 98% of people's goals power wise. (Not sure what other options are out there now, but replacing the TPI was usually an $800+ investment which pushed up the cost of a build vs an LT. Not to mention the early ECM is not the best...)
Just my opinion, but I think once you've removed the TPI unit, be it an aftermarket intake on an early car or owning an LT based model year, the LS gets a lot less attractive for like 98% of people's goals power wise. (Not sure what other options are out there now, but replacing the TPI was usually an $800+ investment which pushed up the cost of a build vs an LT. Not to mention the early ECM is not the best...)
Race Director
Joined: Sep 2001
Posts: 14,676
Likes: 751
From: NEwhere Ohio
The only advantage an lsx swap gives is lighter weight.
that is it. period.
an iron block lsx provides no advantage unless you
a. Get it for cheap
b. Plan on building it for > 1300 rwhp
that is it. period.
an iron block lsx provides no advantage unless you
a. Get it for cheap
b. Plan on building it for > 1300 rwhp
Last edited by dizwiz24; Aug 27, 2019 at 11:39 PM.
Pro
Joined: Mar 2000
Posts: 690
Likes: 7
From: Bradenton, FL
Cruise-In II Veteran
You could just change the cam. That will make a world of difference. I don’t think changing the heads will make a whole lot of difference. You’ve already got more than enough torque available. My 427 drives well with dart 215’s and an xfi280 cam on 3.73 gears. (I do have a dry flow port injection system., otherwise, my build is very similar to yours. The street drivability issue I see is mechanical noise from those short fat pistons slapping around whwn its cold.
Last edited by Z51BOB; Aug 27, 2019 at 10:39 PM. Reason: Clarification
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
I have a 1990 C4 with a ZF-6 speed, and 4:10 gears, Stage 3 clutch with a single mass flywheel. TPIS Headers ceramic coated, Corsa Exhaust.
I built a 421 stroker a couple of years ago, and was power hungry. Here's the rough engine specs.
Dart Shp Block
4340 3.875 stroker crank
6.0" Oliver billet rods
Srp forged pistons
Comp Cams 236/245 @.050 duration, 5.70intake .574 exhaust 113 LSA
Dart pro1 230cc cylinder heads
Air Gap RPM intake
Comp Cams magnum 1.5 Roller Rockers
Howards +.030 Bar lifters for the Dart Block
MSD Distributor
FiTech 600 power adder Throttle body EFI self tuning
Here's the question. I sold my C5 last week, and am considering trying to tame the C4 into more of a daily driver type car (it has air conditioning). Should I get some AFR 210cc heads and a 225/235 ish cam as a good streetable setup? I'm going nuts trying to decide on cylinder heads and cam because everyone I ask about it is leaning in hard on it making 600 plus HP (let it rev / breathe...big heads and cam)..I really want it to drive nice. Or is that too much to ask.
I'm also considering an LS Swap, but am not sure if I could figure out what to do with all the wiring....and what to do with the 421 that works terrific except a little rough for a street engine. Plan B could be to just get a C5 Z06.
Any and all suggestions/opinions are welcome.
I built a 421 stroker a couple of years ago, and was power hungry. Here's the rough engine specs.
Dart Shp Block
4340 3.875 stroker crank
6.0" Oliver billet rods
Srp forged pistons
Comp Cams 236/245 @.050 duration, 5.70intake .574 exhaust 113 LSA
Dart pro1 230cc cylinder heads
Air Gap RPM intake
Comp Cams magnum 1.5 Roller Rockers
Howards +.030 Bar lifters for the Dart Block
MSD Distributor
FiTech 600 power adder Throttle body EFI self tuning
Here's the question. I sold my C5 last week, and am considering trying to tame the C4 into more of a daily driver type car (it has air conditioning). Should I get some AFR 210cc heads and a 225/235 ish cam as a good streetable setup? I'm going nuts trying to decide on cylinder heads and cam because everyone I ask about it is leaning in hard on it making 600 plus HP (let it rev / breathe...big heads and cam)..I really want it to drive nice. Or is that too much to ask.
I'm also considering an LS Swap, but am not sure if I could figure out what to do with all the wiring....and what to do with the 421 that works terrific except a little rough for a street engine. Plan B could be to just get a C5 Z06.
Any and all suggestions/opinions are welcome.
Melting Slicks
Joined: Mar 2002
Posts: 3,108
Likes: 126
From: S.L.C. UT
I agree with Brian. I think some AFR 210s would make more power, and pick up torque with a smaller port and more air speed. You could sell your Dart heads to offset the cost. I think a cam like you mentioned would also work well. I have built alot of 421s, and you wont want less cubes after having one.
Last edited by tpi 421 vette; Aug 27, 2019 at 11:51 PM.
Le Mans Master
Joined: Feb 2005
Posts: 6,479
Likes: 565
From: Clearwater Florida
..... It sounds to me like you already have a street engine … I occasionally drive my 421 powered vette on the street and it didn't get too gnarly until I put a spool in it … 261/266 @ .050 with .700-ish lift … this with a TH400 (no O/D) and 4.33's … mine is not daily driver material at all but its a hoot to cruise around in ! … its just hard to keep it under 200* in traffic …..
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 810
Likes: 58
From: Alva Florida
C409, Looks like your a few hours north of me!
!
It actually isn't all that bad to drive on the street. The problem is that it really struggles when the a/c kicks on at idle, it runs hot in traffic (I have a dewitts radiator, and a spal fan setup), and when in parking lots it jerks around quite a bit. I have to keep hitting the clutch to keep it from bucking. Part of me says to live with it, part of me says new heads. part of me says new better velocite heads and smaller cam. I've asked a lot of professionals about this also, and the response is pretty much the same.
Some say heads, some heads and cam, and some say let her make the power she was meant for......decisions, decisions.
!
It actually isn't all that bad to drive on the street. The problem is that it really struggles when the a/c kicks on at idle, it runs hot in traffic (I have a dewitts radiator, and a spal fan setup), and when in parking lots it jerks around quite a bit. I have to keep hitting the clutch to keep it from bucking. Part of me says to live with it, part of me says new heads. part of me says new better velocite heads and smaller cam. I've asked a lot of professionals about this also, and the response is pretty much the same.
Some say heads, some heads and cam, and some say let her make the power she was meant for......decisions, decisions.
Race Director
Joined: Sep 2001
Posts: 14,676
Likes: 751
From: NEwhere Ohio
C409, Looks like your a few hours north of me!
!
It actually isn't all that bad to drive on the street. The problem is that it really struggles when the a/c kicks on at idle, it runs hot in traffic (I have a dewitts radiator, and a spal fan setup), and when in parking lots it jerks around quite a bit. I have to keep hitting the clutch to keep it from bucking. Part of me says to live with it, part of me says new heads. part of me says new better velocite heads and smaller cam. I've asked a lot of professionals about this also, and the response is pretty much the same.
Some say heads, some heads and cam, and some say let her make the power she was meant for......decisions, decisions.
!
It actually isn't all that bad to drive on the street. The problem is that it really struggles when the a/c kicks on at idle, it runs hot in traffic (I have a dewitts radiator, and a spal fan setup), and when in parking lots it jerks around quite a bit. I have to keep hitting the clutch to keep it from bucking. Part of me says to live with it, part of me says new heads. part of me says new better velocite heads and smaller cam. I've asked a lot of professionals about this also, and the response is pretty much the same.
Some say heads, some heads and cam, and some say let her make the power she was meant for......decisions, decisions.
and it will have nice streetmanners
Last edited by dizwiz24; Aug 29, 2019 at 11:44 AM.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
I would try to just swap cams. Contact a couple cam companies and see what they suggest. You might contact fitech if they have something for a/c compressor cycling. In my case, the A/C would have fallen off when the 421 was instslled.
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 810
Likes: 58
From: Alva Florida
"How about less of a cam but a blower (or turbo) - to more than make up for what you lose with a smaller cam"
That's a good idea. I have a toledo pro high rise hood, so maybe I could squeeze that in there ~ even with 5 lbs of boost it would scream!......great suggestion!!!
That's a good idea. I have a toledo pro high rise hood, so maybe I could squeeze that in there ~ even with 5 lbs of boost it would scream!......great suggestion!!!