I know a guy who put a mutha thumper in a 350 chevy,.030over,aluminum heads,750 holley,etc...nice little street motor.Heres my question,he claims its making 550+ hp.Do these cams make that much power?550 horses out of a sbc is a stretch,not impossible but it takes a lot of work.Is he close or just talkin' the talk?
well if that is the case my 350 bored .60 over with 305 heads and a 7102 cam and flattops with a rochester q-jet should be at 1200hp.
I have a guy putting a 350 together for me. Over the counter zz4 heads, 272 comp cam, Keith black pistons, 9.7 to 1 compression ratio. He is experienced and says it will be an honest 385 horse. I believe him. Don't know if that helps or not.
It can be done but.....Show me the dyno sheet. I got so sick and tired of when people asked me how much horsepower was my motor putting out, Id tell them and they wouldnt believe it, that I now just carry a copy of the dyno sheet it the glove box. That shuts them up. Maybe the guy has a pair of those 100hp chrome valve covers on the car ;-)
You can claim anything you want as long as you don't have to get out on the track or on the dyno and prove it. 350 sounds more realistic and may be a bit on the high side.
My 2cents - Not enough specs to give even a good calulation but with the information that was posted I would say that the numbers are high.
not a chance in heck. those cams are actually engineered as much for making noise as they are for performance
Just my $0.02. The Thumper cam series seems to be about having a nasty sounding engine that has good driving manners - as oppoased to having a real nasty HP engine.
I just put a 355, scat rotating assembly[10 to 1],dart pro one alum. heads ,full roller thumper cam, edelbrock rpm intake ,edelbrock carb, msd ignition.NOT a combo I would normally put togeather BUT it was what the customer wanted . Anyway we ran it on the dyno and it made 417 hp and 409 ft lbs . dropped right off at 6300 , I would have guessed 370 to 380 hp at best . So quite the street engine that sounds great and runs on pump gas with power acc.
There's more than one "thumpr" for SBC, so it's hard for any of us to say it's impossible. Is it the flat tappet MT, or the roller? They are different specs, and will develope different HP in SBC if all other specs are equal. The roller thumor is duration 299/319, lift .531/.517" in a SBC. Pretty stout for any SBC build, but will make a lot of high rpm power. I still doubt 500+ hp, as that's really getting into rare air for a SBC build. But depending on all the particulars it could be over 400 hp.
The only way to believe that claim would be with a (real) dyno sheet. I'm with milner3268's post for sure though, even though the marketing and premise behind the thumpr series cam rubs most of us the wrong way, they're just like any cam in that they'll make respectable power with the right combo.
Many events have a portable chassis dyno available for a small fee. They are also called a humbling device. No dyno sheet, no time slip, no.
well some here are throwing out #s with out any info. like compression for one.size of the cam etc.and that's just to start with. ive byuilt 600 hp sbc. and you could have built a house for what it cost back then.and it was more than just buying parts. I remember when everyone was trying to get a true 300 hp out of their sbc.on the street. hell a 1974 350 2barrel came with 145 hp.i cant count how many guys but a 4 bl carb and acam and headers and yelled 325 hp lol
I saw the car pick the front tire up over a 12 oz coke bottle on a paved highway with street tires. Honest!
Instead of asking us why not have him put his money where his mouth is. I am a believer in the little engine that could but it seems like a 500+ HP small block is not going to have very pleasent manners on the street.
Maybe if he was running a stroker crank, and an 850cfm carb, he could get to the 525hp range if he knew how to build it, as opposed to just bolting together parts. most hot rodders are just mechanics--pull off the offending part, don't fix it, just replace it with something else. nothing meant against mechanics, but most fix by replacing, not by taking the part apart and fixing the part and reinstalling it. ask the guy what RPM he's making the power at with only 355cid...it better be 6000+.
Rather depends on the size of the horses. Shetland ponies or Cleveland draft horses. Same with the dyno - 6.00 am on a cool humid morning with the mercury high, flash reading - world of diffference from a sustained pull on a hot dry day. However I would tend to believe him but I might just beat him in a race with my 350 HP engine!
HP can be anything you want to say it is. I don't believe many dynos either, only as good/honest as the operator. I've seen 450 HP outrun 590 HP personally!
I've seen a few 550hp sbc motors but they weren't 355s or streetable. And that power was at about 7000 rpm. An optimist at best.
I have the receipts to show on the 350 in our pickup and I would hesitate to claim 550 HP. Our specs are as follows; 4 bolt block +.030 with a forged DSS racing rotating assembly and 18cc dished pistions, Comp Cams NX262 series induction cam, lifters, springs, magnum rockers on Dart 180cc runner 76cc aluminum heads a 142 CID Weiand supercharger and 700 CFM Holley, MSD mech advance disributor and 6BTM controller. The boost gauge reads about 5 psi under load. It runs nice and likes expensive gas!
I'm a little skeptical of a 550 HP/350 street engine too. Take it to the track, then run it across the scales. You can get a pretty good idea of what you've got. OK, what do you call a guy who fixes stuff instead of replacing it?
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