Crower cams info/input please?

[zdatsupra]

So the few finally ruined the cam thread for the rest of us who can use it for info etc,
After flipp flopping for the last few weeks and waiting on my engine builder and he waiting on me I told him I was going to trash the idea of upgrading cams right now.
SO now I am having second thoughts about passing up on the cams and have some questions:
The scenario is my build already has the eagle rods, .040 over cp pistons and a balance on the bottom end.
I told him to do his good valve job and put some good flow work on the head.
I plan on doing 15-20 lbs boost on my sp61gt that Im running with my 750s and the megasquirtII.
Im interested in increasing horsepower wout boost.
Now Im thinking of at least getting the smaller set of cams and springs only.
To save cost, not purchasing the valves and leaving out the extra 200 bucks to install them.
If I ask my builder he is always for more the better so I rather not ask him.
So my questions are:
Can anyone sum up what I will be limiting myself too by not installing the larger valves? any benefits to actually keeping the smaller valves? if larger is better go with 1mm over vs just the .5mm that the group buy offers?
Knowledgeable input much appreciated please, I want to decide by monday so my build doesnt get held up any more.
Thanks

 

[Doward]

It depends on whomever is actually doing the port work. I don't believe there is any problem with valve shrouding (haven't gotten that far in my build, yet ) so I'd go with the larger valves.

Since you are standalone, I'd go with the 272s. They are, imho, probably one of the best 'street cams' (based on specs and theory, anyway) that I've seen. Good, aggressive ramp + midrange duration + extra lift = good in my book any day

With your standalone, I would go new cams/valves > port work, for now.

 

[figgie]

not needed even with a standalone. To take advantage of 272 you MUST (notice the criticality of it) spin the motor upwards of 7500 rpm. SP61 and that aggresive a cam. Overkill for that turbo. Now you would have said something along the lines like A T78, T88, GT40 or GT42 and then by all means.

Pass the cams for now. Until and IF you go bigger turbo then I can see useage for bigger cams but not on a SP61.

 

[jdub]

Figgie - Opinion on the 264 cams and a SP61?

How well will they work with a stock ECU and a mild port?

 

[figgie]

Figgie - Opinion on the 264 cams and a SP61?

How well will they work with a stock ECU and a mild port?

the issue in our head is not the cams. The cams are actually pretty good. The issue comes with the valves sizes (which are TINY) and the need to unshroud them in the CC chamber. 264 cams will probably give a bump in the high end with an sp61 but you will still be at the mercy of the head if it is not worked on. Not to mention with the stock ecu.

IMHO

the 2jz folk have the right idea. Don't touch cams until upwards of 700+ rwhp.

 

[jdub]

Ok...by head work you mean = port, polish, +1mm valves.

Just looking at the 264 cams from a "theory" stand point, it looks like you would get a 20-40 HP increase in mid to high range rpm. That would be due to the additional lift/duration.

Since there are very few 700 HP 7M's out there, sounds like you're saying there is no point in any cams at all for a motor in the 400-500 HP range?

 

[figgie]

Ok...by head work you mean = port, polish, +1mm valves.

Just looking at the 264 cams from a "theory" stand point, it looks like you would get a 20-40 HP increase in mid to high range rpm. That would be due to the additional lift/duration.

Since there are very few 700 HP 7M's out there, sounds like you're saying there is no point in any cams at all for a motor in the 400-500 HP range?

close

by headwork i mean extensive headwrk.

all that you mentioned plus, Cumbustion chamber work to include elimination of all the bumps (between the two valves on both intake and exhaust) and making the CC "tumble" smooth. Then unshrouding the valves which is a task by iteself. Then polishing up the exhaust side up pretty good (myself nothing short of mirror will work, but that is me so don't listen to me) and enlarging both intake and exhaust side which to do correctly nothing short of CNC machining will do.

Cost will be stupid but then we have a head that might flow a tick better than the stock 2jz head.

for 400-500 rwhp. The cam should be the very LAST way to achieve that power. There is power to be had elsewhere.

 

[zdatsupra]

So, are we better off getting larger valves installed with some headwork vs cams. Maybe hold off on cams until a later date?

 

[IJ.]

I have around the 7k AUD in my head and while it may not be "needed" it's part of what makes my motor so flexable and sweet to drive even off boost.

It all comes down to what you can afford/justify as the 7M responds very well to head work.

 

[bowsercake]

Is there an easy way to measure cam lift and duration? As my cams are not in the head yet I bet its pretty hard to measure duration. However, I have measured the lobe heights (with a cheap caliper, accuracy maybe +-.2mm)
__________Stock________Mine
Intake_____38mm________39.7mm
Exhaust____38.2mm______39.8mm

I read on the old mailing list that the stock cams have about 7.5 lift each. http://www.supras.com/pipermail/supras_supras.com/2004-August/005731.html

So, since my cams are about 1.7mm longer than stock, is the lift approximately 9.2mm?

The engine that these cams cam off of was running stock valve springs, and machined stock valves. It was running a T-88 making a lot of horsepower, but I'm not sure how high it was rev'ed. Was running these on the stock valve train, was this a bad idea? Also, are these cams too aggressive for a 57 trim CT26?

 

[Tun_x]

let me know if they dont work out for you ..I could definetly use them.