I wouldn't go that far.

 

Mr Buscher when would this head package be available , I need something real soon .

 

David,
So what do you think of Mototuneusa.com article on HIGH VELOCITY INTAKE PORTS? He states that by actually decreasing the size of the intake ports on the engines he works on he sees more horsepower, because the velocity of the air is increased so when that fast charge of air goes into the cylinder it has enough speed and momentum to keep pushing in just a little more after hitting the piston which is on its way up. This then puts more air into the cylinder and therefore more air/fuel mixture.
But he works with sport motorcycle engines which are extremely-high reving (12-14000rpm), small displacement (.6, 1, and 1.3 liters) and naturally aspirated engines.

What do you think of his research? He has dyno graphs to proof it. I would love to test out his theory if I have a dyno.
He also shows you how to high velocity port your own head.
here are the links:

Part 1 of High Velocity Intake Porting: http://mototuneusa.com/think_fast_intake_porting.htm

Part 2 of High Velocity Intake porting:
http://mototuneusa.com/homework.htm

Thank you very much.
I would really apreaciate your input and not dismiss it unless you have proved it wrong on your dyno.

 

Having been a afficionato of motorbikes myself, Motomans articles are pretty good information. This is the same type of development and research that has been going into F1, mostly N/A, type cars for a long time. The trend, of 'good' port design is acutually catching on in more commercial products. For example...when the TL1000S Suzuki was released, it came with I think 36 or 38mm ports. They were finally downsized to 34mm (I think) which resulted in a more 'low-end' torquey motor., and more consistent powerband. My TL1000S (even with a 'flat' race tune from a dyno has a power spike at about 7200rpm. My butt dyno feels it every time I nail the throttle at 6000rpm and carry it to 11000rpm. This is really unusal for a V-Twin motor) Anyways...that's just an example.

So...what does that mean for an EVO...

Unfortunately the EVO has one more variable that other cars don't have ... a turbo / forced induction. So I don't personally think the Motorman article exactly applies to EVO-land.

Typically turbo based motors (and heads) benefit from a port being 'opened' up a bit. David is really quite knowledgeable about this, and is probably going to try to get the best street tuned / High Performance port job done. Personally I'm glad David is sharing some information right now...especially since he found that the stock EVO head has a 'stall' point. If I'm correct here...that means there is an flow rate that the head really won't like which would could translate into a rough running motor / potential power loss at some band of rpm...

FWIW, HP Street porting in the last few years has gone from super high HP to a long band of 'consistent' airflow to help the motor behave in a predictable and 'linear' fashion.

BTW most cars that run AutoX and / or benefit from a predictable motor setup...versus super high HP 'numbers.'

Cheers,

jcnel.

 

I think, I didn't go back and look, but somewhere in this I said something about how we use to port the heads compared to now.

At one time we basically hogged the port out as large as we could. This made for some great numbers to advertise at high lift. I figured the turbo was going to be pushing the air in anyway and the larger port was best.

I was told by the guy that owns the flow bench I was wrong. I then started experimenting with different port work and found something that actually flowed well in the area where our cams work.

I then took this head and put it on the race car. Well, he was correct. The power overall was improved across the entire curve.

Ever since this time we re-visit the flow bench from time to time to try a new idea or something we heard about.

The EVO head I used all we have learned up to now and am just amazed at what we have gotten it to flow.

The head work is now ready and anyone that needs to have a head done can send it in.

David Buschur
www.buschurracing.com

 

David,

Have you or are you going to dyno with the improved heads to see what kind of power increase we're looking at? How much is it going to cost to have this work done and are you looking at going with larger valves? About how long would it take once you receive the head to have this work done?

Thanks
Matt

 

David:
Thanks for the reply on the high velocity porting, I see what you mean.

But what if we are going to run the Tomei Procam set (260 duration, 11.5lift). Will we still see power all the way to 9-10,000rpms?
Omar

 

so whats the final verdict.. did you end up with larger valves? any power numbers? any updates?

 

The head work is finished as far as R&D goes. We have not dyno'd the car with the head on it. Actually we probably will not be doing just the head on the dyno. I am in the process of building a complete engine for the car and bolting this head on it. There is way too much **** talking in the EVO community about how is and isn't fast. We are going to be going all out on the car in the next few weeks to come, I'd like to put an absolute end to how is the fastest for quite some time. BTW, this is not in regards to anyone that has actually ran a faster time than we have to date. It is directed at all the bench racing shops.

The duration on the Tomei cams is pretty low. The 272's are what make really nice power up around 10,000 rpm. I don't know how a 260 duration cam is going to perform. I know the 264's fall off on the top end compared to 272's.

David Buschur
www.buschurracing.com

 

you mean the JUN 272's right..... cause the HKS are nowhere as good as JUN above 7500rpms

 

 

David,

I'm a big fan of your shop, but I think this is the wrong thing for you to do with the car right now. The bulk of your customer base is looking to do stepwise improvements to our almost new cars and, except for those few who have either blown their bottom end or have more money than the average Evo owner to spend on mods, are interested in delaying a rebuilt bottom end as long as possible. I think we are also very interested in knowing how far the stock bottom end can be pushed and would prefer to see you blow an engine than pull it out preemptively.

I think you actually would get more credit for taking a stock bottom end car into the 10s than a built bottom end car into the 9s. I also think that most people know that your shop has built the fastest 4G63 combos before and there's no reason that you can't make an Evo as fast as any other 4G63 car you've done in the past. I really don't think you need to prove it.

I believe that your core Evo customer base would rather that you continue to see how far you can take the stock motor. If you are putting a built bottom end in before a larger turbo and head, I think the presumption is going to be that you aren't confident that the stock bottom end can hold the power and many of your customers are going to shy away from the parts until they can afford a complete motor. Is that the message you are trying to send? Also, we aren't going to know how much of the power that you see with the new head and turbo is coming from a b&b'ed bottom end with a lightweight reciprocating assembly.

Anyhow, I hope you decide to bolt on that head and do some dynos now. Then bolt on that big turbo and see if the motor will hold together. No one will fault you if you blow a motor making in the mid-500whp range. I could be completely wrong about what we all want you to do, but this is just my opinion.

Love your shop, your customer service and your products. Just hope that you change your mind on this one and put the rebuilt off a little longer on the shop Evo.

 

I agree 100%

 

Yup, wont know what the head is really good for if there aren't numbers to back up the improvement of only changing the head. Even if there are mods, a before the head and after the head installed would be helpful.

 

I'm just saying somebody (Al) tried the JUN 272's vs HKS 272's and made more power up top, so maybe Mr. Buschur might give those a try