Track crew: What do you have in the top end?
 

My motor is coming close to a finish its got belfab rods, supertech 8.7:1 pistons, billett OPGs and a 99 head.

I figure, while its apart we might as well take every possible way to make this thing properly. Which brings me to the head. The 99 head i have needs some new valves. So i figure i might as well make the head bullet proof too, right?

What valves, springs retainers and why?

I am not entirely sure how much hp this motor will see, i dont *plan* on revving it too high probably no more than 7500, but to be safe i figure i should throw some springs in.


High HP track guys, what do you have on the top end of your motors?

I left everything stock with a valve-job. I only rev to 7k because peak torque is low enough that going over 7k isn't so spectacular.

Belfab springs, retainers, and oversized valves, all part of the full HP Kit, on a 99-00 head. I've been revving to 7500 and no problems. The (relatively) large turbo I have should let me get away with upping boost levels at higher RPMs to flatten out the torque curve. Dyno time will tell.

Besides, when I am setting up on the front straight to pass Hustler going into the Rattlesnake at MSR, the overrev will be nice :fawk:

shim under bucket conversion
standard sized valves with the reduced stem
supertech springs, Ti retainers, etc
viton valve seals

they're just all in a box.

I plan on using you and every-other street car on the track as my own personal urinal...again.

I need to do a valvejob. I'm going to add springs at some point. I don't expect to make power up there, but I want the extra 800rpm to play with so I can cut a shift out at a few tracks.

I don't plan to make power up there either but it would be nice to have that headroom.

What are the advantages or disadvantages of oversized valves?

My understanding is that the springs are the weak link for the rpms a race motor will see, does that mean stock valves matched with a set of springs is fine?

I used SI Valves' valves with undercut stems for better flow and reduced weight. Also got the intakes 1mm oversize. Don't have any numbers to compare, but it seemed like a good thing to do at the time. The set was only about $200.

I had a '95 and a '00 head to fool around with when my motor was being built so I had my machinist measure the spring rate for both sets. The '95 head had springs that were something like 7-8 lbs heavier so I used them.

WORD OF WARNING: If you plan on changing the valves in your BP4W head, plan on spending an extra $160 on shims as your lash will need adjusting.

Says the man with a 6spd and 4.1 diff. You could just up the boost and run a 3.6 you know...

Oversized valves will not flow better without headwork to take advantage of such.

Supertech et al valves flow better due to their shape.

Oversized valves, ported and cleaned up head; soft cut at 7250, hard cut at 7500...

- L

snowboardinghomo,
Headwork is great and all, but its a lot cheaper to slap on a 99 head and twist the boost controller. You'll have more than enough power and torque over a wide-enough RPM range that you will not miss the expensive head work especially if you go with that little ass pea-shooter turbo.

Just do a 3-angle valve job and "clean-up" the casting in the runners.

Hustler, i really dont know whats in the future for this motor, heck it might end up being a 400+ motor i just dont know.

I do know, that i never want to open it up again, EVER. I also know that i will be tracking the car on regular basis once it running well again. I also know that i am still learning alot with driving and driving on a track and it would be nice to have that headroom in the high RPMs not for power but for safety. Then again i feel like i am overdoing and overthinking this.


So stock valves, and a set of supertech springs will be fine pretty much for the life of the motor right?

without a doubt. You and I want the same thing...I'm content with 300whp. I don't think you understand how fast 300whp (dynodynamics) really is. You know what set-up I have and if its not the fastest street car on the track on any given track day, its not a mechanical issue...its the driver.

I've seen the TDR car bend a couple valves from an over-rev though; the springs are probably a good idea. Spend the money you saved on Penskes. From this point forward, I'm after real suspension and track time.

God dammit, a hundred and sixty dollars for fucking shims? :vash:

just ask your mom.

Yup. $10ea x 16 and BTW, you'll need to adjust lash if you get the seats cut even when reusing the stock valves. Actually, that's kind of worst-case-scenario. You will be able to reuse some of the shims but without a doubt you'll need to change a few. I bought about 10.

I did the lash myself because my shitty machinist didn't want to do it. If you are doing this yourself you'll need a micrometer or a set of calipers, a feeler gauge, a pad of paper and a lot of patience. What sucks is Mazda has discontinued many sizes you'll have a hard time getting the lash dead-on.

I have a a small cache of shims of various sizes that I'd be willing to trade & I have the tools. Let me know if you need a hand.

Is that retail price or Mazdacomp pricing?

retail

Oh thank god. Mazdacomp FTW.