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4.3 stroker kit?

33K views 32 replies 10 participants last post by  compmikey 
#1 ·
i found a wepsite called speed-o-motive. they seem to have quite a selection of kits availible. has anyone stroked out their 4.3 while adding on a supercharger? any idea what the hp and tq gains might be from just the stroker kit... n/a? the kit i'm interested in claims 8.5:1 my biggest concern is the stock wrist pins being weak. my 4.3 has 235k so a rebuild is needed anyway to get where i want anyway. i have not heard of anyone where i live ever having it done. most people i know have swapped for the v8.
 
#4 ·
How much you looking to push. 5 fly or 5 rear. I would not run speed-o kit. Or at least not for power sake. You can get a hardened piece from RPM and either eagle or oliver rods. And be able to support 500 ponies. I'm doing it now. If you want a stroker crank call Mike at RPM or the guys at Crower. Either way your looking at 2500 bucks and up. Without knowing a budget its hard to point you in the right direction. Crank, rods, and pistons I have a little over 3 Grand in. I get the money stashed away to build the next motor when its time its gonna be close to or over 5 grand for those three components just to buy them.
 
#6 ·
i plan on something obd2. from 97 and up. i'm looking at 5 grand anywhere i seem to go. i would like to know why all my friends say the 4.3 can't handle even 300hp. are they on crack? maybe it's the cost. i'm not that worried about the money. i'll be doing my build in stages and would like to be able to drive it while i work. my van runs very well and i'm not that worried about it's condition. it is in good maintinence. no cold knock. can i just strap a blower on it and run 7psi just the way it is? what about top end, like cam and lifters ect...? i could do a v8 but i think i need the v6. after i'm finished i will park my van and install into my buick regal for the summer. that is why i need 500hp crank/ bhp... how about 500 at the fly for arguments sake
 
#10 ·
That's funny. I'm on a stock bottom end in my '03 and she'll turn 325 rwhp. Parish8 hit around 400 rwhp, so that makes the hp at the flywheel on a couple of 4.3's above that so called 300 mark. There are plenty of others on this site that turn out good numbers.
Smack your friends for their idiocy.

Yes you can run 7psi on a stock 4.3. Biggest issues to tackle will be fueling and tuning.
 
#9 ·
Most parts you can get from Race Proven Motors. My Crank is a stock piece that's been treated and hardened from them.The rods and low compression pistons you can get from them as well. I have Diamond custom pistons, Oliver rods and RPM's factory hardened crank at the moment putting 518 to the tires, with a rough estimate on over 650 flywheel. It can be done. Honestly the simplest way to do it if you wanna drive your vehicle is get a spare motor and build it. I picked the block I'm using now from the local recycler for 150 bucks. Then had the machine work done and dropped my hardware in.
 
#15 ·
Yes, at 4200 rpm my fuel pressure dropped too low and couldn't support enough fuel so we let out. But 360 rwhp and 490 rwtq at 4200 rpm isn't bad. Right now I am in th process of putting the walbro 255 pump in, I also have some 60lbs injectors to go in next time I have it tuned, then turn the boost up a bit more and hope for low 400's to the wheels.
 
#13 ·
if the crank can be chryoed, what else can be froze? there is a company in calgary that will freeze anything. i'm currently looking for a complete donor vehicle. i see some impressive hp numbers on here and if everyone is reliable then i will stop concerning myself. thanks.... and for the record, i'v been researching... i don't see what the issue is with asking a few questions. too bad there's ignorance in every forum. i'll find another place to research.... search button please.... too funny
 
#14 ·
Well, when you frequent a forum long enough, you get tired of the same questions every week over the years. So it isn't uncommon. Calling the helpful ones ignorant is humorous.
Not sure why you question if everyone is reliable. Plenty of builds here to confirm the 4.3 is stouter than most people think. Typical things apply to it just as they would a V8.
Add air, fuel, spark, keep your air/fuel ratio in a comfortable range and see what you get.

Hope you find what you are looking for. Enjoy the forums.
 
#17 ·
Well, when you frequent a forum long enough, you get tired of the same questions every week over the years. So it isn't uncommon. Calling the helpful ones ignorant is humorous.
.
just one person. when someone tells me to search... how did they think i ended up hear. it's like saying we have the answeres but you aren't allowd to ask the same boring questions. patience is deffinatly lacking for the new guys. as far as calling spedomotive questionable, they have been in buisness for a long time and the come very highly recomended by lots of other pros. i also see alot of problems on this site with regards to mpg and generally lots of engines not doing so well. it may have something to do with boost on stock bottom end or people don't care how their vehicle runs untill it don't run anymore. maybe i'm way off base. but it's right there in black and white. i too once thought the stock components would be fine. but i know one thing.... gm didn't intend a 4.3 as a race engine. if you want power you have to make it. stock bottoms not an option for me. where i come from, we call that being cheap. i'm simply looking for the best way to go about my projects. trash talking one company to boast of another is bad for buisness. but hey, i asked for it. i don't want to strap on the biggest badest blower and bottle so i can call a towtruck from my cell phone. 500hp is the mark i want to hit. i can't wrap my head around the stock bottoms holding even close to that for long. i'll keep looking. i still have my 68BBB 430 on standby
 
#20 ·
******* - I'm putting by all guesses 300hp on my crank right now @ 8-9psi. Before extra injectors I ran it up to 9-10psi more than a few times for more than a few seconds up to a 17afr. soo.... ya it takes some abuse. If you want all this hp for all this money and you have an engine sitting in the garage that already has it...
 
#21 ·
******* - I'm putting by all guesses 300hp on my crank right now @ 8-9psi. Before extra injectors I ran it up to 9-10psi more than a few times for more than a few seconds up to a 17afr. soo.... ya it takes some abuse. If you want all this hp for all this money and you have an engine sitting in the garage that already has it...
the car that was supposed to get the 430 went away. the build sheet for that is all in around the same price. big block buicks have their issues as well. these issues to fix would cost about the same. so i'm here researching all of my engine options to see what fits best. thats why 500hp is my mark. i may indeed put the 430 into something like my van or my regal but i like the 4.3, and the 3.8. just for the mpg. out of 3 chioces buick costs alot more. i also live in a climate that is very harsh. not the best for carbs. BBB has big power, but 7.1l will never be good on gas. for 92octane. it costs 1.15+/l. i can literally watch my gas guage go down as i drive. not cool. if i only wanted an engine, it would be a sbc. too bad everyone has one. how many have a 500hp v6?? not as many. how many have a BBB?? but that one is going to cost Big Bucks! the block alone is 5grand, to re work an old block, 3500, hell, the buick paint is triple what ford red is. i'm also dabbling in a rb26dett teritory. i found 1.
 
#23 ·
you can do 750HP on a stock bore stroke 4.3 with a stock crank (nitrided) eagle rods and a set of JE pistons all readily available off the shelf. a 4 bolt conversion would be a smart idea. and a a set of ported vortec heads or if you have some cash to spend you can buy a set of brodix -8's or -10's edelbrock has a manifold 4 barrel available stick a wilson elbow on it and a 90mm TB and a set of 60lb injectors (mike lee sells these already converted to EFI for 650 included fuel rails). but now you have to control it with an ECU and then all tuning ect ect

lots of ways you can swing this bat. best bet is to call Mike Lee at race proven motors/SYTY performance, his TY makes 1200hp out of 282 cubes but with splayed valve V6 heads. he also has a few customers that have a 301/305 cube V6's in the 1400-1500hp range.

a V8 will be cheaper... build a 500hp NA sbc for 5K.

Matt
 
#26 ·
you can do 750HP on a stock bore stroke 4.3 with a stock crank (nitrided) eagle rods and a set of JE pistons all readily available off the shelf. a 4 bolt conversion would be a smart idea. and a a set of ported vortec heads or if you have some cash to spend you can buy a set of brodix -8's or -10's edelbrock has a manifold 4 barrel available stick a wilson elbow on it and a 90mm TB and a set of 60lb injectors (mike lee sells these already converted to EFI for 650 included fuel rails). but now you have to control it with an ECU and then all tuning ect ect
I dunno where this 750hp number on a stock 4.3 with upgraded bottom end comes from. Link?
 
#28 ·
I'll test your 750 limit.
If the nitrided crank will hold 750 I will know soon enough. Give or take I'm around 650 flywheel now. And I plan on going even higher. If I get my way I'll be 750 rear wheels. I still got a 150 left in the holster for the nitrous setup I'm running and it's easy enough to run a second line and put my iceman solenoids on with the zex plate I have and don't care for 2 much. And tell the programmer to run 2 stages.
Yes I am that crazy:D
 
#31 ·
I saw stroker kit, then something about a stock nitrided crank handling 750...I'd like to see this...................................
 
#32 ·
I'm going after 2 guys I know one has his rusty horse. His best run is 9.1 at 141. Puts down 786 to the rear tires on 37 lbs of boost. The other one has his bottle fed Camaro. His best run was a 9.01 at 142 on a 300 shot. Since I only have 6 slugs not only can I weigh less even though the truck weighs as much as a boat anchor weighing in at 3470 with me and I'm aloud to weigh 2700. I'm not limited on power adder size or stages.
 
#33 ·
Even the budget priced Speedomotive assembly is $1500. That's a lot of coin to get 10 more cubic inches of displacement. You'll net way more power with a decent SC or turbo setup and later model heads. I've run 22 lbs of boost with stock 4.3 wrist pins. Where was the source of this concern?
 
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