4.6LPoppy

This will be either the third or fourth time I've posted this thread and it keeps getting pulled and stuck in "General Discussion". I can't think of much more technical than cam specs, but, oh well. If this doesn't make it either I will contact you guys who were involved with the discussion by email.

VT Competition Engine Development (formerly VT Engines) will have a new cam available next week which I really like. Here's why I like it:

Cam specs: 222 Intake / 235 Exhaust duration, .567 Intake / .540 Exhaust lift, 114* lobe separation angle (LSA) on a billet steel blank.

Why do I like it? For my application in a 2000GT 2v w/ blower, it has a moderately increased intake duration of 222, but with a MUCH higher than stock .567 lift. This moderate duration high lift combination is excellent for low end torque which is not normally the strength of the 281 cu in motor. The 235 exhaust is a moderate/mildly aggressive increased duration with a mildly agressive lift. This will get all the gasses out without exhuast pulse backup into the chamber. The increased LSA of 114* keeps the centerline of the lobes sufficiently separated so that there is little, if any, overlap between the intake and exhaust valves being open at the same time. This is what blower cars need so that the quickly loading intake air does not escape through the exhaust valve during overlap. On a NA engine, overlap is good because it has a "drawing" effect on the air flow, helping the exhaust gasses escape and sucking the intake air in. You don't need or want that with a blown motor. With this LSA and moderate durations with high lifts, this cam will load lots of air very quickly into the compression chamber while not allowing it to escape through the exhaust. Think of it like this: You can open a door to an air-conditioned room for 5 seconds (duration). But it makes a big difference to how much cold air you loose whether you open it 1 foot or 2 feet (lift).This cam loads lots of air quickly with little or no loss through the exhaust. It also will increase my rpms and shiftpoint from 6100-6200 to about 6500 (estimated). The power band will also shift to the right and gain power all the way to the higher shift point. With the blower that is great, because "more rpms, more boost, more horsepower.........IF you can flow the air!

I know off-the-shelf cams won't work for everyone, but this is almost exactly what I wanted for my P12SC s/c'd 2V. But, having been designed for a 4.6, I think it is the best off-the-shelf grind I have seen for a 4.6 blower setup.

Some of you guys who were involved the last couple of weeks in this discussion wanted to know these specs. Here they are. I hope this post doesn't get pulled. (You think the moderator is a sales rep for another cam company?)

97targa

You can have any cam with any specs you want custom ground by VT I thought?

4.6LPoppy

You're right. I'm only saying that they will now be carrying this cam in stock and there has not been an off the shelf grind that works real well and was designed for a blown 4.6 before (that I'm aware of). They're selling them for $559/pair. It's just FYI info since the Comp Cams and Crane, etc.off-shelf stuff doesn't really come too close to a blower cam spec. Some setups may still benefit more from a custom grind.

10inch Terror

I designed the cams for VT Engines when I was there and all my blower grinds worked great. I still do my original grinds under my own company now.

4.6LPoppy

Did VT stock blower cams or just do custom grinds when it was in business? I guess you were there when it was VT Engines before VT Competition Engine Development? You do custom grinds now---where/info?

10inch Terror

Yes...we had our reg grinds we sold all the time. I was formally Jim@VTEngines on the boards. You can find the cams in my store in my sig.

4.6LPoppy

OK. I posted this talking about this VT cam and how I liked it. I still do, but several suggested I call Tim at Modular Powerhouse and I did; twice. He was really helpful and I got a lot of good info about my setup and he made a cam suggestion. So, I went with it! I still like the VT cam described here, but I liked Tim and his knowledge after I called him as a result of the info I got from this post. [sm=chattypair.gif] Nothing against VT Competition Engine Development opr their cams.