Cylinder heads, short blocks, flow benches....
 

Hi guys,

As you all know, or should, we have been building these 4g63's for just about 15 years now. We have the shortblocks down to a bulletproof combination along with the cylinder heads.

We haven't had our EVO engine/head apart yet. We have ordered in all the needed parts to get the ball rolling on the new style engine.

We sent out to have custom pistons built a few weeks ago and we got them in last week. Problem is there was some type of misunderstanding and they came in wrong. I should have the correct pieces in my hand in another week. The factory piston is the nicest piston I think I have ever seen come out of a stock engine. I don't see any problems making well over 500 whp on that piston if the tune is right. The rods are another ball game though. The rods are already addressed by the aftermarket and we have them instock.

The cylinder head. We have a brand new head and it goes on the flow bench next week. Right after we will detroy it with band saws and porting and see what can be done with it. There are alot of companies porting heads and alot of claims being made.

One thing you have got to keep in mind is this. EVERY single flow bench flow differently. I would really like to think this is the case and that the 6 competitors heads I have flowed over the years on our bench aren't liars. We have numbers for our heads and they are useless, atleast in comparison with other companies. Until the heads are flowed on the same bench the numbers mean nothing. Reading that someone flows 330 cfm on their 4g63 head is nice. Problem is they don't advertise if it is intake or exhaust, how many inches they flowed it at or if they cheated and bolted tubes to the runners. It's mostly a bunch of bull**** you get. As I said, of the 6 other heads we have flowed NONE of them outflowed what we are producing. We have seen two of the 6 flow damn near the same but none more.

One other thing you need to keep in mind is you need to know what lift the head was flowed at. Flowing this head and advertising a flow number at .500 lift is useless. The biggest cam we run and most of you will ever run is only around .420 lift. Porting one of these heads to flow from 0-.420 lift is alot different than porting it to flow from .400 and up. We have learned to concentrate on nothing over .450, it does nothing for performance.

These are my opinions and as all of you know I sell parts. Take them for what they are worth. I would gladly compare in person for anyone one of our heads against something they have done though.

We have finished testing on the EVO valve springs/retainers. They suck. Well let me rephrase that. The springs suck. The retainers are BAD!! A Crower titanium retainer weighs in at .008 kilograms. The stock EVO retainer weighs in at .004 kilograms. I was really hoping to use this retainer. It fits nothing out there though. The coil bind numbers on the stock spring are also the highest of any Mitsu spring we have tested, stock. As far as seat and open pressure they are the weakest spring we have ever seen. A 100,000+ miles 1g spring will test much higher than these. The springs need to be addressed for sure. I am surprised we aren't seeing failures even with the light valves that they have to control.

I am hoping that within two weeks we will have our heads ready for sale. We won't have cores so we are going to need them sent in. I won't sell any ported heads until we have the numbers on the bench where we want to see them. I am hoping for great things.

Hope you guys find this information useful.

David Buschur
www.buschurracing.com

Great information!

Damn tuition! I can't wait until this summer...I'll be spending some dough with Buschur!

Damn what don't ya'll do!!!!!!!! :headbang:

Ok, let me see if I understand what you're saying.

Stock valve springs = bad {thumbdwn}

Stock retainers = lighter than Titanium aftermarket= good ?? :confused:

What is max lift on the stock Evo cam? How about the HKS 272 and 264?

Are the stock springs safe with the HKS 264 intake and exhaust cams? Plenty of room from coilbind even with the tall stock coilbind height you mentioned?

Do you expect that with your ported Evo head that you will make significantly more flow in the lift range of the stock cams, or will the ported head really not make sense until you go with higher lift cams?

Thanks for any information you can share at this time.

Any ideas on what you will charge to do the head? Are you going for a larger diameter valve or is this question too early until you see the flowbench numbers? I know if you open up the passages too much with natural aspiration you can loose velocity to the point where you are actually loosing ground, especially in the low end. Dose having the intake charge pushed into the head alleviate this problem to the point that you can open it up a lot more do to the velocity of the intake charge being applied by the pressurized intake tract? I guess that this is really not important, I am simply curious. If the exhaust designs are completely different between naturally aspirated cars (you need some back pressure) and turboed cars (you want as little backpressure as possible) I do not see why the design of the intake ports could not follow a different theory of opperation as well. Sorry for the long question. :)

Also...What rods do you plan on using? Would you recommend 'Groden' Rods...the ones Shepard uses?

Maybe the stock EVO springs aren't bad for the cams that are in it. I can see why it might be bad if you're upgrading to cams with higher lift and duration. Have you have measured the spring rates of the valvesprings? You don't want a valvespring thats too stiff, otherwise you will lose a little power as it will require more force to rotate the whole assembly.

Dave, why are you so down on the rods? Yes, they look just like the 2G rods....but the 2G rods are cast and the EVO rods are forged units. We now have a shop making 551 HP at the wheels on the stock bottom end, so I think the rods should hold up just fine for anyone wanting 500 HP or less :)

Keith

What advantage does a head have? also will it cause a CEL?

Hmm - time to do some research into WORKS' springs/retainers set ...

Just because some shop makes 550whp on the stock parts doesn't mean the internals will take it for very long. Even Martin knows the car is a bomb at that point. How does the evo head compare to the 1g dsm head flow wise? I've heard that the ports are much smaller.

I agree 100%. More spring pressure wears out parts and eats power. You should always run the least pressure necessary to control the valvetrain, and I haven't heard anyone complaining about floating valves in the stock set up at high RPMs.

I agree with you 100%.... I was just pointing out that our stock rods can take a hell of a lot more power than 2G DSM stock rods. The stock 2G rods let go around 450 HP at the wheels even in a well tuned car, and we have now seen 550 on stock EVO rods. I personally am aiming for 400 HP at the wheel daily driving and 500 on race gas only at the track. I now feel confident I can achieve this on the stock bottom end.

Personally I hope Martin keeps pushing till the stock bottom end lets go so we have a definitive answer....but that is not reasonable to expect from anyone :) My view is to take whatever someone else says is the MAX anyone has gotten from the stock bottom end and put a 150 HP safety margin on that for daily driving on pump gas and a 50 HP safety margin on it for race events on race fuel.

Keith

Not to bash you, but how do you drive a 417hp evo and not know what a head is? :confused: