engine size autocross

[c3rocket]

Thanks for the advice guys I only autocross this thing 10 times a year tops and what about a lsx 427 but I think I would still have to swap exhaust out.I auto cross with a fast bunch of guys and 2 of them have small block chevys and there about the fastest out there a ls would be nice but I would have to scrap all the stuff I all ready did for the car like a complete march serpentine pulley set up and my quick time bellhousing and custom side pipes.

[dontlifttoshift]

In case images don't show up. https://www.m3post.com/forums/showthread.php?t=102981 Here's the M3 on a chassis dyno. Kansas has more peaks than this torque curve. So yeah, great engine for autocross.



Go back to the OP. The 427 will be easier to drive than the 377, it makes more power everywhere, will require less maintenance, be more fun and driveable on the street and he won't have to regear the car to get it to dig off a slow corner

[c3rocket]

I have everything set up already with my march serpentine pulley set up and my quick time bellhousing also my custom side pipes and I only autocross 10 times tops a year and I think it will just be easier to put a 396 up the the 454 blueprint maybe with fuel injection a couple of guys in the group I autocross with are very fast and run small block chevy motors and I am not trying to be the fastest guy out on the coarse .

[Vimes]

Thanks for the advice guys I only autocross this thing 10 times a year tops and what about a lsx 427 but I think I would still have to swap exhaust out.I auto cross with a fast bunch of guys and 2 of them have small block chevys and there about the fastest out there a ls would be nice but I would have to scrap all the stuff I all ready did for the car like a complete march serpentine pulley set up and my quick time bellhousing and custom side pipes.

You'll have to swap the exhaust out with a big block anyway so I wouldn't let that stop you from doing an LS. A small block is EIIEEIIE, while an LS and a big block are both EIEIEIEI, with E being exhaust and I being intake. Your exhaust will not bolt to a big block. And, depending on how large your exhaust runners are you might need to change the exhaust anyway if you go with a big cube engine.

If you're set on part re-use your best bet would be to stick with a small block. You could just do up an aluminum 400 small block and it'll bolt right into where your current engine is. Or, stroke the same 400 out to a 427. I've never used these guys before (their link was first in my search) so can't say they're good or bad, but they offer an aluminum small block 427 short block for 5500 bucks. And, Chevy Hardcore goes over their build that they claim is a streetable 600HP, but there's no dyno along with it. They did say you want an aftermarket 400 block for this as factory 400s are prone to cracking out when you stroke/bore them to the limit. For autocross, and just general fun-to-drive, I'd be looking at aftermarket aluminum anyway.

[dontlifttoshift]

Big block was never on the table.

I was thinking about a blue print 427 or 454 small block the 454 makes 580 hp at 6000 and 570 trq at 4600 .

[short&wide65]

In case images don't show up. https://www.m3post.com/forums/showthread.php?t=102981 Here's the M3 on a chassis dyno. Kansas has more peaks than this torque curve. So yeah, great engine for autocross.

Funny, because it is the car to have the SCCA's FS class where it routinely beats the Camaros and Mustangs in the class. You obviously haven't driven one.

[dontlifttoshift]

I have, along with the Mustang in FS trim and the Camaro 1LE trim in BS trim.

Nonetheless, in your need to argue you inferred sarcasm where there wasn't any. My apparently unclear post agreed with your comment about how great the M3 engine is for autocross and it supports my assertation that a flat predictable torque curve is better to drive.

[short&wide65]

Nonetheless, in your need to argue you inferred sarcasm where there wasn't any. My apparently unclear post agreed with your comment about how great the M3 engine is for autocross and it supports my assertation that a flat predictable torque curve is better to drive.

I’m not trying to argue at all. You said that a destroked high revving engine can’t have a flat torque curve and I disagreed.

[c3rocket]

Well with out having to change any thing I really like the small block 454.I have a detuned little 350 making 600 hp and and 600 trq at 4300 and love it and its very manageable and predictable here it is .

[c3rocket]

The 454 small block will be close to that very user friendly.

[68Formula]

Vacuum on the BP SBC 427 and 454 are extremely low (values are listed on their dyno graphs). You'll likely need manual brakes, hydroboost, or a cam with less overlap. I would not be surprised if that's also the reason they don't offer the Sniper EFI as a package on that one (insufficient vacuum for speed density).

On the 400 they claim 10.5" Hg @ 950rpm. Still low, but might work with power brakes. It's also offered with Sniper EFI. Torque is really flat and really wide. And if you went the EFI programmable timing map you can fine tune the power(take some out the bottom to soften it if necessary, or take some on the mid-range and really make the torque flat and predictable) even more. Or setup two tunes, so you have one specifically for autocross, and a second one for street/strip. The bore is the same size as the 427 and 454 so no bore valve shrouding. And it could rev a little quicker as it less stroke than the larger two.

Since the image won't seem to post for me, I'll just post the link for reference: https://cdn.shopify.com/s/files/1/21...g?v=1626803310

[c3rocket]

My car is manual brakes with a willwood big brake kit and will be using a e vac system for the crank case .I would run a fuel injection if I know it will not be a pain in the ass to fine tune .

[Vimes]

Big block was never on the table.

Missed a word - my bad.

[c3rocket]

I know late but here's a update I ended up going with a 434 small block from skip white racing with flat top pistons and the shorter of the two they offer team g intake it has dart shp block and afr 220 heads toped off with a holley xp 950 did 652 hp and 608 trq and I can run my ac and has vacuum, the only problem I am having auto crossing is in turns and stopping in the stop zone it cuts out so now I am putting in a new fuel tank with the sniper stealth fuel injection .

[Hopperj7]

For autocross, you really do not need as much power as you think. I had a friend who raced a bone stock LS1 in his first gen Camaro and always killed it. Too much power and you risk losing control or fighting the car.

[BonzoHansen]

...,the only problem I am having auto crossing is in turns and stopping in the stop zone it cuts .

I have that same issue on hard stops. Not turning though.