Tomei cams

[flatrate]

where does the head get machined to compensate for the additinal lift?

[julio]

where does the head get machined to compensate for the additinal lift?

[flatrate]

i assume it gets machined out where the cam lobe "swings" so to speak...

[Darius]

Yep. There's a picture somewhere in the RB forum of NICO that shows someone's work on the cam lobe relief grooves to accommodate a high lift cam. They pretty much just took a carbide bit to the edge and knocked it down until the cam cleared it. Nothing really scientific about it except you can't cut it below the "ring" on the hydraulic lifters or they won't pressurize and you'll have problems. I am not sure how much material must be removed but if you absolute cannot avoid cutting the reliefs down below that ring on the hydraulic lifters, you'll need to consider switching to a shimmed solid lifter valve train and cams for solid lifters. Now you're talking big-boy money!

[flatrate]

really wish i would have modded the head before it was installed now damit

[Darius]

Don't worry. Plenty of power can be put through the stock head and valve train.

[flatrate]

yeah i dunno very few people are getting impressive power out of stock heads... with reasonable boost and pump gas ive pretty much done everything i can think of to help this thing make power.. and its not even close to making what i expected

[julio]

yeah i dunno very few people are getting impressive power out of stock heads... with reasonable boost and pump gas ive pretty much done everything i can think of to help this thing make power.. and its not even close to making what i expected

I know its probably on the forum somewhere, but whats your setup/power output?

[flatrate]

yeah i dunno very few people are getting impressive power out of stock heads... with reasonable boost and pump gas ive pretty much done everything i can think of to help this thing make power.. and its not even close to making what i expected

I know its probably on the forum somewhere, but whats your setup/power output?

RB25
AFI divided T4 manifold
3076r with 1.06 divided housing
greddy style intake manifold
full 3in exhaust
haltech ems 850cc injectors
bottom end is built.. stock head/cams

at 20psi it made 412whp and 320wtq id like to get close to 500whp on pump gas pretty far off

I did have a pretty large boost leak pre intercooler @ the BOV during the dyno... the engine is run on a map based setup so no maf

No idea what kinda power loss a boost leak will cause, i know its servere on a MAF car but its not a maf setup... havent dynoed it since the boost leak being fixed but dought it did much

my honda made 480whp and 360wtq at 18psi and pump gas on the exact same turbo..

[RustspecS13]

Even with a map setup a boost leak will cause a big power loss. The ecu is seeing whats going in the engine, and the afrs and all that are right, except the turbo is overspinning for that boost. IE you might be loosing 5 psi (random number) and so the turbo is maxing out at 25psi, yet the ecu/engine only see 20, so it makes less power.

I would get bigger cams though, even just slightly larger.

~Alex

[flatrate]

Even with a map setup a boost leak will cause a big power loss. The ecu is seeing whats going in the engine, and the afrs and all that are right, except the turbo is overspinning for that boost. IE you might be loosing 5 psi (random number) and so the turbo is maxing out at 25psi, yet the ecu/engine only see 20, so it makes less power.

I would get bigger cams though, even just slightly larger.

~Alex

im curious to try some regrind cams cause there so much cheaper but havent deceided

I need to put the car back on the dyno to see if it gained power... id be surprized if it gained more than 15whp