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I read a post that used the company name Extrude Hone out of Irwin Pa. I checked out their web sight and they show some pricing for doing V8 exhaust manifolds for $675.
http://www.gethoned.com/parts.php?get_price=yourparts&show=automotive

Has anyone tried this? If so, do they give a flow rating? Does anyone have any real-world experience that they can share? I hear that they are only worth minimal, but I am looking for actual numbers if anyone can help.
I have read other posts about this process, but I am looking to see if anyone has any dyno or time slip results to compare.

Thanks

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Waste of money

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Thank you all for the quick replies.

I was reviewing the process for my 70 340 HP exhaust manifolds. I am currently trying to decide on a Winter project, and I am considering the Dougs or TTI headers. But when I read this thread, it got me curious when the price was lower than the TTi's. I will assume that the extrude hone will not give the performance of the Dougs/TTi's, but that got me curious to see if anyone has done any testing of their own on this process to see that the actual gains may be.

Thanks for the pictures Scott!!

I have emailed them to see if they have done any of their own flow/hp/tq tests but I have yet to hear back from them.

Thanks again.

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There's a post in the race forum here on Moparts about F.A.S.T. intake/exhaust manifolds and there is some real-world feedback.

Darren

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want to thank everyone for their replies.
I just received an email from Extrude Hone and this is what they said for performace gains on exhaust manifolds:
""Rick says that after processing the average airflow increase is 15% with an approximate 15 to 20 horsepower increase. The cost to Extrude Hone process your exhaust manifolds is $675.00 (per pair) plus shipping. The turn around time will be approximately two weeks""

I just wanted to pass on the information.

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SKATPAK,

All due respect, nobody is arguing that headers will out perform factory manifolds, of course they will, especially a warmed over engine. The question is, how much gain will Extrude Honed factory castings offer over untouched castings, and is (whatever that gain is) worth it?

Scott, it seemed that the original poster was considering going with headers and I just posted an actual comparison between the 2 different setups. No doubt that headers make a big difference in a warmed over engine! But in my opinion the extrude process is not worth the money for the small gain if any.

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I just reviewed the article in Mopar Muscle when they dynoed the 7 different exhaust manifold/header combos and I am still surprised that the TTI's were only +16 ft/lbs and + 12 hp over the 70 HP units on the mild small block. I know that the numbers will go up as a motor gets more modified, but I am still trying to justify the price of the TTi's (apx $740) and the Doug's (apx $550) and the Extrude Hone (apx $675 + shipping) for only 16ft/lbs and 12 hp maximum gains.

I just want to thank everyone again for their replies and their experiences on this subject.

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Well if you BELIEVE what Extrude told you you'll see the same increase from their process as the TTi's ...

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Folks I will post a real world comparison next week. I have a set of untouched factory 71 A-body 340 manifolds as well as an identical set that have been Extrude Honed, both will be tested on the same engine with no changes and the same pair of exhaust pipe extensions. Keep in mind that any gains (or lack of) may vary with ANY engine combo, it's all about where the engines "bottlenecks" are, if it's the exhaust manifolds (which is what I expect mine will be) you might see a bigger gain with EH manifolds, in my case will will soon see.

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I agree, I have examples of both, PS 71 vs 72 I can see zero difference, also no difference betwen DS 71's and 72's in regards to internal shape.

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Almost 7 hun for a set from EH ? .... it used to be under 4 hun !!

I say PAY yourself almost a HUN per hour and do-it yourself. I spent about 6 or so hours on a set of 69 HP B engine ones and were more than pleased with the results.

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You can do the extrude hone process oh proctologist of fibberglASS ???

please elaborate

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You can do the extrude hone process oh proctologist of fibberglASS ???

please elaborate

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Well here we go again folks! Walk over to the window and look out.

FULL MOON ON TUESDAY!

FEEL THE LOVE

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thanks for posting that rear wheel dyno result

is the 5 hp gain
with the Extrude Hone exhaust manifolds
about 1.5% or so
of the maximum horsepower?

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John I can't answer the AC questions yet but I'll ask, I believe it was removed completely, I also believe it was a stock filter.

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Hey Scott, can you post the sheet...and what happened to the "15 to 20 hp" ??? You could easily loose or gain 5hp with the choice of muffler you run and on a real 340 CI motor the gains would probally be less than 5hp. I remember when Dulcich dynoed a 440 and gained 2-3 ftlb of tq with the extrude honed BB set...not really worth the effort and expence AND I hear that some exhause manifolds will crack over time. I would like to have seen that 426 run with a nice set of TTI headers as well as the manifolds.

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Extrude Hone CLAIMED 15-20 , Scott was alot closer with his 5-10 guess

Why am I not surprised to see the unrealistic claims from someone taking your hard earned cash?

Reminds me of someone else

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if the post-Extrude Hone manifolds are still off the engine and available,
perhaps it would be a good idea to make some templates of the port shapes the EH process created?

if these templates were then scanned and added to the archives,
perhaps other factory manifold owners using a grinder could be very close to the gains found?

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I think I picked up a total of 12HP on a "back to back" test. That was on a 12 to 1, 484 cubed Hemi... making Huge power .

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There; I fixed that for you.



Dave

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Doug Dutra cast some new split /6 exhaust manifolds from scratch. For that kind of money a person could almost recast a set with a bigger ID. Just thinking out loud

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Well, I don't know if that would work or not, but let's say for a minute that it would, if you can get a set of (outwardly accurate, internally larger) exhaust manifolds cast for $600.00 please sign me up!

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As far as Dudeks Hemi picking up 12HP, I have no doubt that he did, as I said above:

I think there is a limit to gains you can expect but IMO every engine will benifit differently from it. As I've said before, you chase the bottle necks in the combo, if the bottleneck is the manifolds it will make a bigger difference and push the bottle neck to some other area needing improvment to gain more HP.

His combo obviously needed more exhaust flow and the EH process helped his engine in that respect more than it helped mine.

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Could be Dave, pure guesswork at this point.

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