Don't worry folks no change of plans on my combo. This is for a friend.

I'm looking for some cam selection help on the centrifugal supercharger combo below. This is a street/strip car. He's wanting to stay with a hydraulic roller. Max RPM no more than 6500, which that may even be a problem since the valvesprings that will be required due to the boost may wreak havoc on the hydraulic lifters. Probably going to run a rev kit to help with this.

I'm think of something like 240/250 @.050, .550 lift, 114 LSA.

Here's the combo:

D1SC Procharger 12-15 psi boost - intercooled
4.125" bore Bowtie block
8.7:1 SRP pistons
3.875" Lunati Crank
6" Manley H-beam rods
AFR 210 Heads
1.5 rockers
Holley Superram intake (320 cfm) - Fuel injected
1-3/4" headers
3-1/2" single exhaust with Flowmaster
3.27 gear
26" slick
700R4
3000 stall converter (with 355) expecting 3600+ with new combo.
3430 lbs raceweight (with driver) - 3rd Gen. GTA

You're definately in the ballpark on the cam, your specs are *very* similar to my current cam, which is 242/254 @ .050 on a 114 LSA. I'm also running a hydraulic roller. My valvesprings were 125 closed / 325 open when new, and with an AFR Hydra-Rev kit I commonly spin it to 6500 with no issues. It's seen 6800-6900 a couple times with no discernable valve float, but I don't like spinning it that high.

However, one suggestion: think about upping the compression to around 9.2:1. It will help out with overall engine efficiency. Even then, no matter what compression he decides on, definately ceramic coat the pistons! It's worth the extra few bucks. Also, if it's going to be seeing a lot of heavy throttle use, it would also be a good idea to spring for inconel exhaust valves IMO just for the peace of mind. Might want to think about MLS head gaskets (Cometic, etc) for durability, but make sure the surface finish on the block and heads are smooth enough for them to seal up properly.

That combo should work fantastic. It's very, very similar my engine combo, and also nearly identical to a friend's car. His car (406 sbc with a D1SC) made 691hp at the wheels on 91 octane with no intercooler. Haven't got mine to a dyno yet, but based on my friend's combo I'm hoping for ~625 rwhp.

You might want to consider calling the guy that helped me out with my combo, Scott at SDCE in Rhode Island at 401-732-4047. The guy builds a LOT of centrifugal blower motors and REALLY knows his stuff. If you can provide your combo details, he can design a cam specifically for your application.

Troy

Thanks Troy. All good suggestions. I'll pass them along.

I've talked to Scott before when I was thinking about a supercharger for my car. I'm definitely impressed with him. I've tried to get him to talk to Scott a few times but he won't do it for whatever reason. He's been calling all of the cam companies and is getting frustrated with suggestions all over the map. I'm just trying to give him a hand and get him back on track.

What lifters are you using with the AFR rev kit? He's running Crane hyd. roller lifters and is under the impression that the AFR kit won't work with them.

Who ground your cam for you?

Jason, I'm using Comp HR's. I already had them and didn't feel like changing them. Didn't have any issues with the AFR rev kit, although I did have to fabricate a support for the center as my Dart heads don't have any support provisions in the middle of them.

My guess is there is something about the top of the Crane lifters or their tie bars that won't work with the AFR kit's lifter buttons.

As far as my cam, Scott designed it for me (taking into account displacement, head flow, etc) and he had Comp grind it. One thing about the Comp HR's, make sure you run a GM Melonized gear on it. DO NOT run a MSD Melonized gear on it, even though MSD says their gears are OK to run on an HR. I've had one MSD/Comp combo totally chew itself apart, and another set was giving out after 7500 miles. No HV oil pump involved, either!

Troy

Thanks Troy.

From what I found, there aren't a lot of hydraulic roller lobes to choose from. It looks like Comp is the only one currently with a few in the 240+ range in their Extreme HR Line. Lunati may have something not listed on there website though as I know Harold is working on some new lobes.

Given that he is looking at 414 CI @6500 RPM, I'm probably going to steer him toward 242/254 @.050, .540/.580 lift, 114 LSA.

Thanks,

Originally posted by DragRacer:

Given that he is looking at 414 CI @6500 RPM, I'm probably going to steer him toward 242/254 @.050, .540/.580 lift, 114 LSA.

Thanks, That's my cam exactly, lift and all. It runs surprisingly well, good low speed manners around town, the idle sounds fairly healthy, and so far I've pulled just shy of 24 mpg on the freeway. Very compatible with EFI, no shortage of power either. It's installed on a 108 ICL (I think that's where I put it, either there or 106, can't seem to recall at the moment) per Scott's recommendation; this gives fairly standard intake timing (which centrifugals like) but because of the wide LSA the exhaust stays open quite a while, which boosted engines prefer.

With proper tuning I don't think your friend will have any issues putting down >700 rwhp on pump gas, and I'd say >800 rwhp will be a strong possibility on race gas and the higher timing you can run with it.

While you didn't mention them, I would start with 75# injectors at the minimum; he also might want to jump straight to 95# injectors to have some headroom. I'm running 55# injectors right now. While I haven't run WOT all the way up to redline yet (broke the rear end while tuning WOT a few weeks back, now I have to take it easy on the new gears for a bit), I was seeing high 89-90% duty cycle numbers at 5500 rpm and I wasn't at full throttle yet. I'll be moving up to 65# injectors for some extra headroom; my friend runs 65# injectors in his 406.

Troy

I'll be moving up to 65# injectors for some extra headroom; my friend runs 65# injectors in his 406.

Troy That's 75# injectors!

Jody

I'm running the Comp NX284 hydraulic flat tappet in my Procharged BBC (blowthough with a carb from Scott). My car weighs 3800 lbs and I've ran over 128 in the quarter so I'm approching 700 hp with only ~5 psi boost.

Originally posted by camcojb:
That's 75# injectors!
Jody LOL, brain fade on my part. Was up at 4:30 this morning and I'm more than a little delirious at the moment.