I helped tune a 508 inch big block today that had a Sniper with Hyperspark ignition. This is a street/strip type of engine with 10:1 compression, big Comp street roller cam, ported Indy intake, Trick Flow 270 heads and a good valvetrain. (T&D rocker arms, dual conical valve springs, etc.) So not a race engine but a street engine with really good parts in it. I think it is a Molnar 4.250 crank with 7.100 long rods and Diamond dish pistons. So better quality parts than a lot of street engines. It ended up making 710 hp at 6300 rpm and 640 torque somewhere in the low 5000 range. I didn't keep a copy of the dyno sheets since it isn't my engine. This engine really taxed the Sniper throttle body, we could tell it was choked off by 6500 rpm. So a big carb, or a bigger throttle body would've added more power up top. However, the guy wants to run the Sniper since he mostly drives it on the street. He only takes it to the track once or twice a year. It is going in a RoadRunner with a Dana 60 and four speed so he is going to have trouble getting the car to go straight!

Nice numbers, Andy. Can you share the cam specs?

Nice project 👍

Nothing special on the cam, it is just a 260/266 street roller with 1.65 rocker arms. Might be a little on the big side for a street car but the guy has a four speed and deep gears out back and he just drives it for fun. He wanted 700 hp and we figured that cam would hit the number. Just barely made it with the Sniper. With a big 4150 carb it would make more power but then the guy would give up the digital jetting and timing.

Nice build. Wish Holley offered the HyperSpark in a stand alone version for carb guys.

Right on you're becoming Mr. EFI

Andy, this sounds very similar to my build. Was there any additional porting or cleanup done? What about any port matching for the intake? Just trying to get a feel for what to expect for final numbers.

The heads are out of the box except for the valve spring change. The intake was ported since it had the typical Indy port mismatch issues.

Any worries about exceeding the stock block's limits at this level?

Thanks Andy. I was shooting for 750-775 and think I'll be close. I've got 526" with a smidge more stroke, a tiny bit more cam, and the extra porting work brought up the mid and top range numbers(378cfm@.700) so I will hopefully be right there.

I don't think the block should be a problem with 10:1 compression and 6500 rpm redline but you never know. We told the owner to shift it at 6200 rpm and just let the torque move the car. No reason to beat the thing to death.

Andy, do you know what lobe family on that Comp cam?
and and what spring pressure it would require?

Thanks, Mike

I have much the same. With lower rpm use, pump gas, etc. hoping that combined with a relatively light rotating assembly keeps my block together. I am at a little more with the 200 shot of nitrous we are trying now.

Mild 600hp driver with 200hp on demand. LOL.

The cam is just a Comp street roller, same basic thing you can buy from Summit. Should work fine with the roller cam springs that come with the Trick Flow heads. The biggest street roller Comp shows in their catalog is the XR292 but this was one size larger which would be the XR298.

That will be a fun street motor.