Don Terrill’s Speed-Talk

Has anyone here ran the 225 shocker series head from Promaxx ?
They look good on paper. But that doesn’t tell the whole story..

https://promaxxperformance.com/product/ ... 5-sbc-cnc/

Baaahahahaha 725+hp..... yeah even on a happy dyno they wont come close to that.

I have used a few sets supplied by the customer. Just another china head. stem clearances were all over the place but runable, valvejob was runable, but in my opinion the hardware they come with is junk. but they will run.

did a 383 that made 525hp with them and a 385 that was never on the dyno.

I only have one experience with Promaxx heads.

Someone brought in a CNC’d Ford Windsor Head to flow test.
I looked on the website and I only found one choice for that...... so I assume that’s what I had here.

The flow numbers were quite a bit lower on my bench than what was on the website.
Enough different that I questioned whether the head I had in my shop was the same as what’s on the website.

As already stated the clearances will need to be checked for the guides, the valve job etc. The non cnc 225s made 509hp 435 tq on a 10 to 1 355 oval track motor with vic Jr and
a 650 holley. The cnc ported heads look ok for what they are and the price but if you look at a set of Cnc Darts, Brodix or Profilers you will see a big difference. The 225 non cnc look pretty ugly when you get the valves out where they can be seen well. Basically it looked like they ran the cnc cutter into the intake side of the runner and then stopped it just on the backside of the short turn if your looking in from the intake side. This left a big ledge on each side of the port and in the roof before entering the bowl area . It looked like someone went in with a really heavy hand and tried to knock the sharp edges off of the roofs of the intakes and they were gouged up pretty bad. The cnc heads are better but there's a reason they're priced as low as they are.

First off if your motor is only 355 cid, or even 383 cid you will need to be buzzing it well .above 8K rpm to make good usage of 225 CC SBC heads

mag2555 wrote: ↑Wed Jan 13, 2021 7:31 am First off if your motor is only 355 cid, or even 383 cid you will need to be buzzing it well .above 8K rpm to make good usage of 225 CC SBC heads

It’s a 434 cubic inch engine i have. Maybe i should have mentioned that.. I’m looking for good heads, that can use a standard rocker arm. I’we been eyeballing the 225cc Brodix Dragonslayers as well. I just haven’t heard many reviews on these heads.

Those Brodix heads , AFR heads and Edelbrocks and Dart heads will all sever your quest very well, and I don’t think that in terms of 220 to 225 CC version of any of these you will find anything more then a 8 hp differences on the average build in your cid range.

Monza355 wrote: ↑Wed Jan 13, 2021 8:34 am

mag2555 wrote: ↑Wed Jan 13, 2021 7:31 am First off if your motor is only 355 cid, or even 383 cid you will need to be buzzing it well .above 8K rpm to make good usage of 225 CC SBC heads

It’s a 434 cubic inch engine i have. Maybe i should have mentioned that.. I’m looking for good heads, that can use a standard rocker arm. I’we been eyeballing the 225cc Brodix Dragonslayers as well. I just haven’t heard many reviews on these heads.

go bigger.

mag2555 is wrong.

What’s the rest of the combo and how much power are you trying to make?

Many a large displacement (for the engine family) engine built with “budget” heads have been a big disappointment.

If you’re building a torque engine they might be just fine, but if you want serious power, you need to offset the rockers to get a sufficient sized and shaped intake runner on the engine.

rustbucket79 wrote: ↑Wed Jan 13, 2021 9:55 pm Many a large displacement (for the engine family) engine built with “budget” heads have been a big disappointment.

If you’re building a torque engine they might be just fine, but if you want serious power, you need to offset the rockers to get a sufficient sized and shaped intake runner on the engine.

A torque engine needs to fill the cylinder sooner. Sometimes a larger head will make a bunch more torque than a small one.

but i do agree with you.

Offset shaft rockers really aren't much more expensive than stud mount, with good studs and a stud girdle. LGM/Probe has some affordable shafts, then again you can get offset stud mounts but only about .200" offset.

They are comparable to AFR 220cc heads, They will really SHOCK you if they don't meet your expectations!

rustbucket79 wrote: ↑Wed Jan 13, 2021 9:55 pm Many a large displacement (for the engine family) engine built with “budget” heads have been a big disappointment.

If you’re building a torque engine they might be just fine, but if you want serious power, you need to offset the rockers to get a sufficient sized and shaped intake runner on the engine.

That’s what i’m afraid of. Thinking back i wish i would have went with a 406...

Save up and buy the correct heads/rockers/lifters. Nobody has been disappointed by overspending on the top end.

rustbucket79 wrote: ↑Thu Jan 14, 2021 11:13 pm Save up and buy the correct heads/rockers/lifters. Nobody has been disappointed by overspending on the top end.

Are there any options out there other then AFR ? Or is that the way to go ?