dereknkathy

you trying to start the "what is wrong with AFR exhaust port" fight again? you must be really bored...and haven't AFR heads changed a bit since 2004 when this thread was alive?

MILD THUNDER

I found the information interesting, mainly looking for Dart head exhaust port modifications, and found this thread. It's also interesting, that a couple people posting in this old thread, saying how great JimV was, and how he improved their afr heads , were also in the more recent thread, saying how he was full of chit, and couldn't improve on the afr's ports. I didn't see anyone calling BS when he said he could improve the Darts ports, or Merlin head ports on this site.....

Has the head changed since 2004, I don't know. Maybe, maybe not.

offshorexcursion

Interesting info

Especially all the hypocrisy!

But I do believe Jim V knows his stuff!

But there's more to heads then a flow bench, and there's more to flow then just max flow at max lift.

I also believe that it splitting hairs between an out of the box AFR CNC and a Dart CNC. My friend built a nearly identical build to mine except Dart CNC vs my AFR CNC and the power difference is negligible... Fwiw

Black Baja

It's a good thing a flow bench doesn't reflect the performance of AFR's exhaust port. If that was the case knowing how most OSO members are I think at some point in time there would have been a lynch mob at AFR's door step.

SB

I began my high performance endevours when there was no aftermarket heads.

We are in a wonderful place now. And have been for a bit.

Many of our aftermarket factory replacement heads now a days, are so well designed/produced, it is extremely difficult to see much more hp / boat speeds from trying to make them better........to go further, ports raising and shallower valve angles with more compact cmbustion chambers will need to be used....which, is of course avalable from many aftmerket head manufacturers. Again, the 24/26* BBC heads are pretty close to being as best as they can be for our use of them..in todays world.

BenPerfected

Part of Jim's Dart Iron Eagle work was for our 500 CI engines we still run today. Jim was able to get the Dart I.E. Heads with modified 323 cc intake runners to flow the same as the AFR and his exhaust ports exceeded the AFR #. These engines with dyno headers made 800 HP @ 7000 RPM at Sterling. This 1.6 HP per CI is great result for any NA BBC design. There is nothing wrong with the ARF heads, but Jim can add to the AFR results at a competitive price and set them up to ready to bolt on.

SB

Oh schit. I met you. Ha ! You had one of those motors at PRI a bunch of years ago in Orlando? It had lifter sprayers if i remember right - that and you where one of the few 'places' for 'marine' there...is what made me walk over and check it / you guys out...lol.

Precision

It's also a good thing that an engine dyno does.

BenPerfected

SB...correct, one of these engines was in the MRE booth. Mike Riley and I along with Keith Eickert will be at the PRI Show in Indy in Dec. Will you be going? 11 years later, Mike is going to refresh these engines this winter.