Cammed S/c Efi 5k

[rockinrolla]

The question is, is it worth putting a mild camm into an engine that is supercharged , intercooled and efi, will it give any real bennifit or be a waste of time ????????? :D :hmm: :hmm: :hmm: :hmm: :hmm: :hmm: any comments are appreciated on this subject.

[coln72]

guessing at this but as long as you don't go stupid with the overlap it would be good

[WinKE55]

I have been informed that the best cam for a forced induction is a stock cam because of the overlap.

 

There are cams for supercharged/turbocharged engines but really it's up to you. My dad is a mechanic and has seen tests done against a forced induction cam and a normal stock cam and said the stock cam was better, not by much though.

[oh what a nissan feeling!]

It is definately worth putting a bumpy cam in, can release large amount of power.

 

Overlap is not a big problem with superchargers, can be a problem with turbo depending on rear housing size.

 

definately worth it!

[irokin]

It is definately worth putting a bumpy cam in, can release large amount of power.

 

Couldn't agree more. In my SR20 going from stock 240ish degree cams to HKS 264s netted a 30kW gain on the same boost... without dialing them in. Just be aware that you will be sacrificing low end power by increasing the size of your cams. It wasn't too bad for me but a little sluggish off boost now.

[Red_rocket]

I Have that the problem with the cam overlapping in my turbo EFI 5k

 

The car doesn't run well at all, i was told the cam is too lumpy!

 

So now i need to change it back to standard! but i can't find one ANYWHERE!! :D

[irokin]

Whats the cams specs?

[Red_rocket]

Whats the cams specs?

 

 

Is this one for me? lol :D

 

If so i wouldn't have a clue?? that's what i was told its overlapping!

 

And the cam was in there when i got the motor! but it was running

 

A carby turbo setup!

[Trev]

Lift is good with boost as it allows more flow, I'm going to run large cams in my 4agte and hopefully i wont have over lap.

[oh what a nissan feeling!]

Turbocharged motors respond the same if not better, to the same mods as a non turbo.

 

Large cams, oversized valves, huge ports,

 

all of these thing can get you more than 1/3 more power with the same turbo on the same boost.

 

There are two changes that you can make to a camshaft, overlap and lift.

 

Lift generally requires bigger and better valve springs, the larger you go, the heavier the springs. Turbo cams mostly consist of lift.

 

Duration is how long the valve is open for, overlap occurs when the exhaust valve is still closing when the inlet valve has already begun to open.

 

This is not always a bad thing on a turbo engine.

 

This is where it comes back to the size of your rear turbo housing, and pressure ratios.

 

The exhaust gas will exit the easiest way, if you have a large rear housing on your turbo,

turbo manifold pressure will not exceed inlet boost pressure, in this case, a large overlap cam is not a problem,

because exhaust gas will continue to exit the easiest way- the exhaust.

 

If you are running a small rear housing on your turbo, the exhaust manifold pressure will exceed inlet boost pressure,

in that case a large overlap cam will allow a small amount of exhaust gas to be pushed back into the inlet.

The result is detonation.

 

I Have that the problem with the cam overlapping in my turbo EFI 5k

 

The car doesn't run well at all, i was told the cam is too lumpy!

 

So now i need to change it back to standard! but i can't find one ANYWHERE!! crying.gif

 

A large cam will always cause a rough idle, i wouldnt be too hasty to remove that cam unless it is definately the problem.

 

The average '30/70' cam is usually ideal for turbo, especially in older motors.

[reTRD]

if ur having troubles trying to find a cam over there you could always try kalford camtec over here in NZ. they are really good at what they do. all you will have to do is tell them all the specs of ur motor, (i.e cc rating, boost u will be running the extent of ur head work if any, and also what petrol u wil run it on and what sort of responce u would like out of ur car and they will work out the best cam grind from there for ur set application. hope u have some luck in finding out what u want/need to no :D .

 

cheers,

Brodie(reTRD)

[untubbed_20]

You can run big duration and lift in a turbo car, but just make sure the

camshaft has a wide lobe separation(114 or higher usually)

 

The current camshaft in my Rb30 run 290 advertised duration([email protected]) and 520" of lift

it has a 118 L/S though.

 

For a K motor i was looking at the tighe 104 or 240 and they said they could regrind it

for me with a 112 or 114 lobe separation for turbo use. Think i am going to go with the

240 with a 114 l/c

cheers

darren

Edited October 26, 2008 by untubbed_20

[untubbed_20]

I have been informed that the best cam for a forced induction is a stock cam because of the overlap.

 

There are cams for supercharged/turbocharged engines but really it's up to you. My dad is a mechanic and has seen tests done against a forced induction cam and a normal stock cam and said the stock cam was better, not by much though.

 

On what motors? k motors? In the olden days that was thought to be correct, same with people

saying it wasn't worth porting heads on turbo cars.

 

These days there are SO many results to back it up, that it is definitly a "old wifes tale"

Most of the cams that lost power in the olden days, had to much overlap, at the end of the day,

most camshaft people where guessing back then(and that wasn't really that long ago, less

than 10yrs)Not like they took every single motor to a dyno and tested them, just ground what they "thought" was right.

I really started to see good results with turbo cars when people started to bring in all the japanese

cams for import motors, or in the case of a peculair workshop like JPC with vl's where they actually

get 5-6 cams ground to there specs and dyno them back to back.

 

But K motor wise, theres still lots to test!, most guys in here use atmo grind cams with small LSA's

cheers

darren

[rockinrolla]

I have noticed differing ideas and problems with a number of things but the main concern seems to be the overlap, as I going to go with the supercharger (sc 12) because I don't Intend to race or drag the car, I just wanted something for out on the highway as that is where I spend most of my driving time, to many cops in Hobart to take the chance of having me car confiscated and it's a bloody long walk home. thanks for all of the info and food for thought, ROCKINROLLA :D :hmm: :hmm: :hmm:

[untubbed_20]

Leave it stock then

cheers

darern