Has anyone tried a 4.030 bore & 4.125 stroke combination? What were the results?

 

IICRC Tim Tosto is running a 421.. running 9s on a 3400lbs car or something like that..

 

You can do a 421 the easy way with an iron block or my way with an LS2 aluminum block (.030" over on the stock sleeve). Check this section for another post on this subject which I have contributed to... I would be interested to hear if anyone else has done a .030" overbore on an LS2 aluminum block other than me...
Shirl Dickey

 

I'm pretty sure tosto is running a 422.


Nate

 

That's the first I have heard that the aluminum blocks could go more than .005" even for the new ls2 variants. I'd be very interested to hear more about your setup. Did your shop do all the machine work and if so are you a sponsor here or could you pm me some pricing info on the 421?

Nate

 

So whats different, beside the 1ci.

 

Actually my motor is a 421 4.030 iron block w/ a 4.125 crank I didn't know how it would work with a big stroke when we built it ,but it has been awesome so far the motor itself is making 700 fwhp 585 rwhp. I shift it at 8000 rpm and it pulls past that. We made a dyno pull at 8200 and it had just started to fall off at 8200 rpm.

 

damn.. wish i had money!

i need to work more

 

Shirl first sonic-test's the cyl's to verify liner thickness, then bases his decision on how much of an over bore the block can safely take and still have a lot of meat left. So far, I think all the LS2's he's built have sonic'd fine with plenty of meat to go 4.030. You can email him at mreracer@tabletoptelephone.com
I have him building a 418cid LS2 for one of my customer's 01 ZO6 that I will install and tune. We (the customer and I) are very excited about this as Shirl's motors always rock. BTW, this 418 is by way of 4.030 bore x 4.100 stroke.
Robert Judd
www.gen3motorsports.com

 

doh! Well I'll pull my foot out of my mouth.

nate

 

Thanks for the input. I'm sorry I forgot to mention that it's an iron block. I have a bunch of misc. parts from other engines, block, 4.125 crank, and rods to build this combo just needed to know how it would or would not work. Thanks again. Great power #'s Tosto!

 

Iron block here. 3350 raceweight. Best of a 9.81 N/A at 138.35 with a slipping transmission, bad torgue converter, tuning issues, bad air, poor track prep and over 300 passes on a tired motor. I can't think of anymore excuses for such a slow ET

 

If 9.80's are slow than I better think of a **** ton more excuses

Nate

 

im with stupid!

 

Honestly I would have to say the gains of a 421 over a 408 would be very minimal if any.

Matt

 

I agree! Especially is your going to hit it over the head with nitrous!

 

I've been getting some feedback for the last couple of weeks. Some opinions which I appreciate and some facts from people who have already tried this combination. I've already built some 402/408 combo's which all have made over 500 rwhp,but the 421's that I've come across so far are all out powering the 402/408's that I've done to date. Both torque and horsepower. I'm never afraid to try differnt combinations. Sometimes you may surprise yourself. Thanks to everyone for their input. Anyone else have something to add, please do so.

 

Morgan Motorsports did this first about 5-6 years ago. 421SD, I think they went 10's back than with a daily driver. I was going to buy one at first.

 

421,422, its all the same the car says 422 in the middle of the hockey stripe,because I couldn't get a #1 emblem

 

where do i get the parts to turn my 6.0 into a 421 ? what will i need