Performance Camshafts for Turbo?

[Shades]

Ok, I'm doing some research on camshafts... I'm gonna grind my BP camshafts, but I'm not sure what's good lift and duration without going over where I have to change the solid lifters to locked lash ajusters or inner shims. I have stiffer springs which have a 12mm max lift.

Here's what I've found...

Stock... Specs
Intake: .319" lift and 196 duration @ .050"
Exhaust: .338" lift and 202 duration @ .050"

Corksport... Specs
Intake and Exhaust: .352" lift and 205 duration @ .050"

Toda... Specs
Intake and Exhaust: .354" lift and 256/264/272/288/304 duration @ .050"

I was thinking .354" lift and 264 duration @ .050" would be good for street use. I'll be running my built up BP and turbo...

Anyone think otherwise?

[Denis]

If you go to crazy with the cam, you will need to swap in solid lifters and you won't idle for ****.

[FE3-323]

what my car is running for cam specs:
Intake: .341" lift and 247 duration @ .003"
Exhaust: .341" lift and 250 duration @ .003"

Advertised mind you.

[BuGS]

http://www.wihandyman.com/forum/showthread.php?t=21754

Check that out.... He is gonna have a setup

[Shades]

If you go to crazy with the cam, you will need to swap in solid lifters and you won't idle for ****.

Yeah I know... I am going solid lifters... but if I go too too crazy I'd have to move to inner shims (shim is under the lifter) or lock lash adjusters (where the lifter is one size and one size only).

[Shades]

These are GUDE (Bullfrog) camshafts... what do you think about those numbers?... since I'm gonna be running solid lifters, wouldn't I use the 00-UP cams?


90-96 MIATA 1.8L DOHC

PART NO: MCZS02
DESCRIPTION: Strong pull from 4000 to redline
POWER BAND 3800 RPM To 7200 RPM
IDLE: Good
SPECIFICATIONS: Intake LIFT - .360 DURATION - 228
Exhaust LIFT - .360 DURATION - 228

00-UP MIATA 1.8L DOHC

PART NO: MCZS04
DESCRIPTION: Strong pull from 4000 to redline
POWER BAND 3000 RPM To 8000 RPM
IDLE: Good
SPECIFICATIONS: Intake LIFT - .420 DURATION - 231
Exhaust LIFT - .420 DURATION - 228

[Shades]

Model Product IN Spec. EX Spec. Specifications
NA8C F-cam 252/9.2mm 256/9.5mm HLA Compatible
NA8C / NB8C F-cam 252/10mm 256/10mm Require Maruha Solid Lifter
NB8C VVT F-cam 252/10.8mm 256/10mm Require Maruha Solid Lifter

NA8C Race-cam 264/10mm 264/10mm Require Maruha Inner Shim Kit /
NA8C Race-cam 272/10mm 272/10mm Require Maruha Inner Shim Kit /
NA8C Race-cam 288/10mm 288/10mm Require Maruha Inner Shim Kit /

NB8C Race-cam 264/10mm 264/10mm Require Maruha Solid Lifter
NB8C Race-cam 272/10mm 272/10mm Require Maruha Solid Lifter
NB8C Race-cam 288/10mm 288/10mm Require Maruha Solid Lifter

NA8C Stock 233/8.6mm 250/8.1mm
NB8C Stock 241/8.7mm 242/8.6mm
NB8C VVT Stock 241/9.5mm 242/9mm

If this makes sense to you... these figures are from Maruha Performance.

I talked to a shop who specializes in this company, and they suggested the intake - 252/10mm exhaust - 256/10mm.

[D323]

since I'm gonna be running solid lifters, wouldn't I use the 00-UP cams?

No the 01+ Miatas use VVT... you'd have to engineer a way to incororate that into the system.

99/00 cams are non VVT and meant for solid lifters... those are the ones you want.

[Shades]

I keep forgetting about VVT... I'll have to call and ask if those are VVT cams or not.

I can't believe the price on cams (not reground)... they're more than I anticipated.

[goldstar]

The Master Speaks

Reference: Maimum Boost, by Corky Bell; Chapter 13, pages 163-64

CAMSHAFTS
"Make no mistake in the fact that turbo performance cams are very different from atmospheric performance cams.The characteristics of long duration and high overlap for atmo cams are unwelcome in a turbo system. The street turbo, which is generally small, operates with exhaust manifold pressure somewhat higher than intake boost pressure. This situation, when presented with long-duration, high overlap cams, creates a huge amount of reversion. Thus the "turbo cam" tends to become a low-duration, very limited overlap cam."

"RULE: It is hard to find a turbo cam that works better than the stock item."

"Is it necessary to change the cam?
No, decidedly not. Stock cams usually work excellently. For the absolute last word in a super-boost (15 psi) performance turbo car, a change of cam will be necessary, but so will several other things. Leave the stock cam alone and you will generally be much happier."

Happy Motoring!

[Shades]

Good post goldstar!!!

I have Maximum Boost and are reading it... I just haven't gotten to that chapter yet.

I guess I'll try and see if my cams can be ground with more lift with the duration untouched or lessened a bit.

Thanks again!

[goldstar]

Glad to help.

Happy Motoring!

[D323]

excellent post.. I was unaware of that... I really need to get a copy of that book... I have been meaning to for some time.

[MD323]

No the 01+ Miatas use VVT... you'd have to engineer a way to incororate that into the system.

99/00 cams are non VVT and meant for solid lifters... those are the ones you want.

I was reading on one of the miata forums that the VVT was no good for boost. they where all complaining their cars ran like ass whent he VVT kicked

[FE3-323]

its mainly the overlap thats a concern with boost. note* BP 90-97 N/A has 19° stock while the Boosted BPT has 10° of valve overlap. extra duration is ok so long as your overlap isn't altered much. extra lift is always ok