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Heading to the pump in a couple of weeks to run this 408 I did. It is a purpose built N20 engine for a small tire grudge car.
Running on C16, carb'd and no spray on the dyno for initial tuning.
*Iron 6.0L, 4.030
*AFR 260 LS3 heads
*Cam Motion solid roller, 274/292, .748/.732 lsa 117.5
*T&D shaft rockers
*Wiseco custom piston +5cc dome (12.9:1 comp ratio)
*PAC 1238X springs, ti retainers, locators and locks
*CID 4.0 intake 4500 top carb intake
*Moroso 4 vane vacuum pump and regulator
*Evans 1050 gas dominator
*MSD 6014/LS3 coils
* 2"/2 1/8" stepped headers
This one should rock n' roll pretty good. Will be interesting to see how the AFR heads do. Have heard they have the highest airspeed of the LS3 aftermarkets. Did you do any clean up to the heads or just set the valvetrain up?
This one should rock n' roll pretty good. Will be interesting to see how the AFR heads do. Have heard they have the highest airspeed of the LS3 aftermarkets. Did you do any clean up to the heads or just set the valvetrain up?
I just changed the valve springs they came with to a PAC1238X and touched up the valve job. It was pretty good already. No porting.
How do you like line honing the mains like that? I assume that's mainly for aluminum blocks and minimizing how much material is removed from the block?
How do you like line honing the mains like that? I assume that's mainly for aluminum blocks and minimizing how much material is removed from the block?
The set up is normally what I use on the aluminum LS blocks for the reason you mention. Works great!, virtually eliminates bell mouthing on the ends with the softer aluminum saddles.
I stayed with the set up on this block since I was just sizing for the increased clamp load from the studs, no major changes to the main tunnel.
How did thiis do? I saw the video, but didnt see any results. Anxious to see, any LS3 head 4.0xx bore gets my attention. This one was done right w/ a big boy cam. Do the AFR LS3 heads have a moved intake valve centerline vas stock? i know the angle is stock, was wondering if they moved it over a noticeable amount.
How did thiis do? I saw the video, but didnt see any results. Anxious to see, any LS3 head 4.0xx bore gets my attention. This one was done right w/ a big boy cam. Do the AFR LS3 heads have a moved intake valve centerline vas stock? i know the angle is stock, was wondering if they moved it over a noticeable amount.
The intake valve is not moved.
This one did 705HP/525ft lbs. Peak HP at 7800RPM, Peak torque at 6100RPM - N20 cams (117.5 lsa = torque killer) don't seem to shine on the engine for me, but this will like a 400/500HP hit and should favor the 9" wide slick the car will have!
I would have liked to run this engine with a cam in the mid to upper 260's and upper 270's on the exhaust on a 109 or 110 lsa. I think it would have done mid 700's and close to 600ft lbs.
These are great combos IMO without alot of custom parts.
06-27-2021, 12:34 PM
408 AFR LS3 N20 engine 
