LilJohn

Nothing if he uses something like a 7675... or an On3 76.

If he runs the s400 with a 96mm turbine that camshaft isnt agressive enough on the exhaust lobe, specifically the EVO, to drive the turbine up at its capacity. In other words.. itd be laggy.

Atomic

iTrader: (37)

Around 120lb/min

T76s10

iTrader: (6)

Ok thanks for clearing things up john. How about the tu2 on a lq4? Does that have enough evo to push a 96mm turbine wheel say 1.32 ar? Sorry to thread jack. Thanks atomic, you might be seeing a pm at Some point.

LilJohn

It does depending on what intake centerline you install it on.

But that cam has another issue... too much overlap. The 112.5 lobe seperation is a touch too narrow for efi applications in my opinion. Its got 11 degrees of overlap at .050... I target 2-5.

For a 6 liter and that turbo... i do 230-232 on intake and 238-240 on exhaust.

T76s10

iTrader: (6)

Pm'd you John

71 chevy

iTrader: (18)

The tu1 or tu0 is what i would use, regardless of cam.they will make torque, helps you spill faster, and keep a decent rpm range.you go a little too big on the ivc and evo and you are killing spool

71 chevy

iTrader: (18)

im using a single pattern similar to the tu2, but a little less duration. it lopes at idle, but it spools ridiculously fast(10 psi on the transbrake takes 0.8 seconds,as i said, sick fast), but will rev all the way to 7600, so it is a little big.

the tu2 will actually act a little smaller than my cam though, because the 112.5 lsa has the intake valve closing a little earlier, for a little more dynamic compression. it would work in a heart beat, but be prepared for the engine to rev.

T76s10

iTrader: (6)

im planning to run turbos similiar yours so thats good news, i want fast spool with this build. i seen the youtube vids on your chevelle and that thing launches pretty damn hard. i figured i better go a little big with this cam since i plan on building this motor in the future. thanks

LilJohn

Since when does lobe seperation angle have anything to do with when the intake valve closes??

Intake centerline dictates that. Lobe seperation is the relationship between intake and exhaust centerline.

Lobe seperation dictates nothing about the intake valve events.

LilJohn

Too late of an IVC can affect spool... it reduces dynamic compression.

But how in the hell can opening the exhaust valve EARLIER, at a higher cylinder pressure obviously, hurt spool? Especially considering turbine wheels work off of pressure...

71 chevy

iTrader: (18)

I'll play your game.

tu2 cam, 236/236 112.5 lsa, no advance
x cam 236/236 116 lsa, no advance

which cam closes the intake valve later???

answer that and you have the answer to your question "Since when does lobe seperation angle have anything to do with when the intake valve closes??"


lets think about this for a second. what is cylinder pressure? cylinder pressure is what does WORK and moves the crank. you open the exhaust too early and what happens to the cylinder pressure?
if some is good and more is better, why dont we just have an evo of 90, or even more?

also, what happens to durability of the exhaust valve when we start opening it too early against extreme cylinder pressure?

71 chevy

iTrader: (18)

thank you sir.

i prefer to go a little smaller than a little bigger on cam selection. but thats a personal preference based on having too small a cam and too big a cam.

LilJohn

Dude... really?

In both those cams the intake centerline, lobe seperation and exhaust centerline are all th same because theres no advance specified.

Again lobe seperation angle has Nothing to do with the intake valve events.

You just posted examples where the icl is the same as the LSA.

Considering they are the same since no advance was specified its pretty damn obvious the tu2 closes the intake valve 3.5 degrees sooner. Its intake centerline is 3.5 degrees advanced from the other cam.

Try again.

Gfleck047

iTrader: (1)

I will talk to a few engine builders see what they say about a cam... the turbo I think il be going with a s475 on that note who does everyone recommend to purchase a turbo from

71 chevy

iTrader: (18)

dude... you design cams . I would expect you of all people to know camshaft spec convention.

ie. 236/236, 115(no advance specified) means lsa is 115, icl is 115 and ecl is 115
and 236/236, 115+4 means lsa is 115, icl is 111 and ecl is 119

seriously... if no advance is specified, then the icl = the lsa, if installed straight up. i know you know this.

LilJohn

So since the LSA and ICL are equal all of a sudden the LSA dictates the intake valve events??

Your last post just repeated what i said.

Intake centerline is what affects the valve events. Period.

71 chevy

iTrader: (18)

i guess i should clarify, since not everyone reading it knows the convention, and i dont want to confuse anyone.

LSA does not dictate when the valve closes, the ICL does that. however, when a cam is advertised with no advance figure, eg the tu2 I referenced, then the LSA,ICL and ECL are all the same number when installed straight up.

code4

iTrader: (30)

forcedinductions.com

qqwqeqwrqwqtq

So you've tested EFI turbo combos with more than 2-5 degress overlap @.050 and lost power?

Interesting, as that is not consistent from what I've seen on the dyno and the track.

LilJohn

3 cams...same engine, car combo etc etc.

0,5,10 degrees of overlap. Ivc and evo the same on all 3.

Cam with 5 picked up over the cam with 0.

Cam with 10 picked up over the cam with 5....BUT it was less of a gain than the 5 had over the zero. In addition the fuel needed was more. So again IN MY OPINION we found the point of diminishing returns for what we were doing.

How long we gonna dance this Dance?