I just bought the turbo I've been after and the only thing left on my "big ticket item" list is the cams. I have a set of HKS 264's 8.8mm IN/8.5mm EX. I was just planning on running them, but I had an idea. WAAAYYY back, I remember a shop in Canada running some regrind cams on a KA that made some impressive numbers. The regrinds were by Colt Cams and were using his tri-flow technology. If you don't know what that is, he grinds two different profiles on the two intake cam lobes so that they don't both open and close at the same time. His logic is that the progressive opening and shutting of the valves moves more air because the changes to the airflow is less abrupt and it also creates a lot of swirl in the combustion chamber, which yields a better mixture and better burn. These cause the turbo to spool faster.

I can find info on plenty of NA cars (they're popular with the AE86 guys) but I can't find anything to substantiate the claims of faster spool. This is a street car before anything else, so it needs to spool in a reasonable amount of time, and I'm running a bigger turbo than ideal, so anything I can do to make it spool faster is going to be a good thing.

My goal is 400whp, to spool as early as possible, and peak HP around 7K (6800-7200). Anybody have any input? Run the HKS's, or get a spare set of cams and have them re-ground? Or am I totally off base and should I be getting completely different cams?

I know a guy in Europe, that did that and make his own camshafts, it was on a civic with a B18/turbocharged engine, here's a pic of them :

http://img87.xooimage.com/files/5/4/c/aac1-378afb3.jpg

Any info on how it worked?

So, this took a bit of searching to find Float, but hopefully it helps somewhat.

Colt cams are also referred to as PDM cams, so googling that with "Tri-Flow" may help your searches too.

group-buy-custom-rb25-cams-t289210.html

This is the only substantial link I can find with dyno charts of before/after cams (and I scoured through Google for this s***) The pictures are very hard to read, and I think the X and Y coordinates are manipulated, so you may want to take this guy's word with a grain of salt. But he claims quicker hp and tq, which may very well mean slightly faster spool.

In my opinion, evidence like this isn't enough to warrant purchasing these cams. Until Colt does back to back dyno tests of a turbo motor with a readable dyno chart, I wont be convinced.

Hey Ryan,

The Colt cams actually work and I still have a nice set stored somewhere that I will eventually sell to someone, but not now . If you can recall, these were based off my Tomei 270 (8.8mm) cams in which the intake cam snapped. I have since replaced that camshaft with a brand new unit and now have a gang of high performance cams just sitting in boxes. Based off my experiences with my own HKS camshafts and the JUN units that are in my S13, Just use your HKS units and call it a day. They are perfect for what you are trying to do.

Dee, any input on valve springs. I have every intention of going to 8K with this motor regularly. Any idea when I'll start having issues with valve float on the stock springs and the HKS's?

I can't comment from any experience, but I've always had a theory I'd like to be confirmed. Since there is more duration there is more time for the valves to close, so even with the added lift the duration should help cancel the effects of valve float.

Granted, now I know a lot more and there are other factors (ramp rate on the back side of the lobe being the largest factor I would think), but I think the basic principle is true.

Your options are limited, but you don't need to shop around as the Tomei units are decent enough for most applications. The dual valve spring technology is fine as well, but I'm more concerned about those springs binding and that being the end of a camshaft or both. Also, you can reference the 300zx TT Heavy Duty valve springs as well. I have 16 of these in my S13 and they are getting it done. My sentra uses the Tomei units and I also have the JUN units in my bling engine that has never been installed in a car because I'm constantly adding and removing things internally (stroking is next ). So there you have it

8K is fine. I used to speed shift my DE at 8.5 all day every day and all I did was stretch the rod bolts. The valvetrain was undamaged. 264s are also fine. Boost young Jedi. Revs lead to the dark side. You have a real deal iron block, son. Put 2 BAR to it and see if you need more revs.

You get that downpipe yet?

I know it'll take 8K+ on stock cams, but the increased lift plus revs worried me some. After I posted, I got to thinking about it and realized that changing out valve springs with the motor in the car isn't THAT big of a deal. So I'll keep the stock springs in there and we'll see what it does. I know boost makes power (2 BAR is exactly what I plan on running), but I want as wide of a powerband as possible. In a small displacement motor, it's hard to get a big turbo spooled up, so when it does spool up, I want to run it out as far as I can. Why? Because I'm a jackass and I will inevitably be racing another person at some point. When that happens, I want to stay in the power for as long as possible before I have to shift again... Which just made me realize, I'm probably going to have to get rid of my 4.63 ring and pinion. I don't think they're going to continue to make sense at these power levels.


Yea, I got the downpipe, looks great, thanks!