421 small block dyno flog

[SupStk]

REW,
I'm not sure you can crutch a poor intake port with a cam. I know however the right cam can hide a mulitude of sin in the exhaust.
I read that deal in one of your other posts about having no luck with the smaller cam. Going with the 102 centerline sounds more like a small engine at altitude trick. Other than that i don't have an answer for you.

You don't have to feel bad abut having answers, the more I learn the dumber I feel. Wish I was 35 years younger, I was way smarter then.

[Joe Mendelis]

[quote=

Only a 215cc head on a high comp 421ci sb?

If setup right a 421 with 14.4:1 with that cam should spin 8500 easily and be making 800hp with no problem at all.

I'm partially raising the b/s flag on this whole ordeal, nobody in their right mind would cobble a setup like that together.[/quote]


You are raising the BS flag? I am raising the BS flag that a 3.875 stroke motor could make power at 8500 with 23 degree heads. Everyone knows
that just won't happen. (Winston Cup piston speed?) 23 raised runner Pro Topline I have seen make 790 @ 7900 on a 402 inch motor. The cam in that was a 282 296 113 with 800 lift. No std head can do that.

800 hp with 310 cfm 23 degree heads? Come on!

[dbusch]

Chris Uratchko made some killer power on a 420" SBC deal with 23* raised runner Pro Toplines. On a Superflow 901 i think it was over 850hp. Of course, this was a class engine that had a ton of cam lift, way over 16.0 compression etc etc. Maybe he will comment in this thread...


REW, if you are making peak torque down at 5000 you can forget about making any kind of decent power. You could raise that up spending some more time on your manifold. Your induction system is just too small...

[REW]

The manifold is a semi-worked Brodix HV1000 with dom. adapter............doesnt a hp peak at 6400 sound like its low to anyone else? I realize the smallish heads factor, but damn.

[REW]

the guy operating the dyno just pulled off a 355 sbc with a similiar sized head and similiar numbers.............274/278 @ .050 .660/.640, Brodix T-1 head, 308 @ .700, same intake as ours HV1000, 13.5-1 comp, and a 900cfm pro systems 4150, and made 606 @ (I think 7300). Isnt there a certain amount of power to be had from just cubes alone? Not to mention more camshaft/compression? Heads being small or not? A 310 cfm runner should be capable of how much power? 650 at least? Im confused as hell.......

[REW]

by the way....I know the peak torque on his 355 was 6200, dont know what it was though.

[Robert Kane]

The numbers seem way low. I would expect peak HP @ 7500+-. The 215's seem too small for the 421 (You stated that) I am thinking the ports can't keep up with the piston speed beyond 6400. 310 cfm should be good for 650 hp, and at 421" it is only 1.5 hp/ci , have you looked at all the other possible areas to limit the rpm? Don't get too focused on a port/manifold problem until you eliminated the other things first. That can get expensive.
Keep us all posted.
Robert

[REW]

well.............fuel is definitely there.......Valve spring pressure is 240 seat, 600 open. I cant imagine the manifold being too small........My buddys 406 shifts (and likes it) at 7800 with a measly Team G manifold. Could it be an ignition problem? Im sure doubtful......Im sure his ignition box and coil on the dyno are fine.....but could it be a distributor prob? Like I said, I dont think so....but most of you know better than I. So, Im game for any explanations. Here is one problem we saw on the dyno..............the distributor is locked out.....and when we set timing the first time, we put it at 34 degrees. Made a light pull........then moved it to 36.......was a little better, and so on....all the way to 40 degrees. Well.......we were checking this at say 3500-4000 rpm..........We discovered that the timing read 40 degrees at 2500, 3500, 4500...BUT at 5500+, the timing dropped to 32 degrees.........and then stabilized again. The cam only has .010-.012 thrust, and the distributor gear is new. Dyno op said that camshaft twist on small base circles can cause things sometimes, sound reasonable? Either way....this wouldnt have anything to do with the low peaks would it?

[REW]

The buddy with the 406 I was talking about made peak hp at 7100 with a 276 @ .050 camshaft and a track 1 head which has VERY similiar CSA AND runner volume to our Dart Conquest heads. Now.....ours has quite a bit more cam, and the same size head........WHY could it peak 700 rpm lower? I mean.......a 421 and a 406 are diff....I agree.......but its not like the difference between a 355 and a 406. I could see a 200 rpm change maybe......even 300........but 700!? And this is with a lot more cam?

[let r eat]

I feel for ya. Hate fighting things myself as well when they aren't making good sense. That duration should have a very noticeable torque climb when it comes in on a graph........Can you tell when the cam is working from the dyno numbers? That duration isn't going to work til 65+ I'd say the 700 rpm difference is accurate between the two engines.
There's allot of good guys on here and I'm sure someone can help ya figure the thing out. You definitely have combo troubles of some type.

[383Malibu]

Chris Uratchko made some killer power on a 420" SBC deal with 23* raised runner Pro Toplines. On a Superflow 901 i think it was over 850hp. Of course, this was a class engine that had a ton of cam lift, way over 16.0 compression etc etc. Maybe he will comment in this thread...

Actually, that was a 415" sbc with 23* AllPro RR-245 heads and made over 870 hp. And it did have a ton of lift and compression.

[REW]

I took the dart conquest heads, and ported a lot more CSA into them. Previously they had been ported to a runner volume of 227 and a .700 flow of 310.5. I removed alot of material tonight, exposing much more area at the pushrod restriction, and ended up with a port volume of 338.5 cc's. The final flow at .700 was 321.6. Any predictions? I sure hope it moves the peak power up.........they look ENORMOUS now compaerd to what they did......

[REW]

we did try a header swap, (started with a 1 3/4 primary and a 3 1/2 collector), and put on a 2" primary with a 3 1/2 collector, and it gained 3 peak horsepower and lost 9 peak ft. lbs. So I suppose it was a wash. Back to the 1 3/4's we go.

[ChrisU]

Chris Uratchko made some killer power on a 420" SBC deal with 23* raised runner Pro Toplines. On a Superflow 901 i think it was over 850hp. Of course, this was a class engine that had a ton of cam lift, way over 16.0 compression etc etc. Maybe he will comment in this thread...

Actually, that was a 415" sbc with 23* AllPro RR-245 heads and made over 870 hp. And it did have a ton of lift and compression.

There's only 2 heads out there really capable of doing that and that is the All Pro RR245 head, another 23 degree head they have, and a Pro Topline RR head.... The All Pro heads are superior castings though.... and very nice material.

[ChrisU]

Three things I see, heads are small, needs a different camshaft if you want to rpm the thing, and the headers are too small... WAY too small.... you have a good torque engine though.