Turbo cam

[Clearlake Kid]

I need to replace the cam in my twin turbo bbc.The only markings on the cam are v25,the motor was built back in the 70's. The motor is pretty much stock,steel crank,forged pistons,after market rod bolts,stock oval port heads with ss valves. Twin Rajay turbos and a single Holley 750 vac. sec. carb.
The motor had 62 hours on it. So i pulled it apart to take a look.It looked good, i replaced the bearings,rings and timing chain. I need to replace the cam now and have no idea what cam to use on a mild turbo motor(8lbs boost) i was told...........Thanks for any input

[Clearlake Kid]

come on guys..............

[05schiada]

Engle makes a few different turbo grinds like the TC 7 & the TC 8. The TC 7 would work better in your application the TC 8 is more for a duel carb set up with more boost. Also Clay Smith has a few grinds available. Ive used both but I would suggest installing some wastegates on your system.

[carreraboat]

Do a search this topic has been discussed here alot you probally want to switch to a roller

[Clearlake Kid]

Engle makes a few different turbo grinds like the TC 7 & the TC 8. The TC 7 would work better in your application the TC 8 is more for a duel carb set up with more boost. Also Clay Smith has a few grinds available. Ive used both but I would suggest installing some wastegates on your system.
What do the wastegates do??? This turbo stuff is all new to me...

[InKahntrol]

I just rebuilt a similar setup... and was told the Engle TCS-7 was a very popular cam on the Banks setups in the '70s. When I went down there to buy one, I wanted to switch to a roller setup and they talked me out of it. Said it cost a LOT more money, and at the power level I was running it wouldn't make much difference.
I ended up using the flat-tappet hydraulic TCS-7 (the engine is a long-rod 496 with 8.5:1 and rectangle port heads), and the cam works GREAT. Excellent sound, HUGE power and torque, but totally usable. It starts with just a tap of the starter, idles without loading up, and made over 900hp on the dyno. Best of all, it made over 500 lb/ft from 2,000 rpm to redline.
Wastegates allow you to set a maximum boost pressure in your system... anything more than that will be released through the wastegates to prevent engine damage. Different springs change when the gates open, controlling how much boost you make in the manifold.
With my wastegates unplugged the engine makes over 15 pounds of boost... too much for me, as I can't afford 114 race gas or broken parts. With the lightest spring in the 'gates, it makes about 7 pounds, which is more what I was looking for.
I had my system rebuilt by Innovative Turbo in Simi Valley. Justin over there is very sharp, and also very patient with me as I didn't know a damn thing when we started this project (and still don't know much). The number over there is 805.526.5400.
Dan

[Lavey Huffer]

I have a very similar set up on a SBC twin rajays and converted to a retrofit roller set up from comp cams.
One thing to keep in mind if you have a prop, is getting a cam that will give you a low enough idle to get it in gear. Call thier tech line and they are very hepfull and the price vs. benifets ,I felt were worth it.

[Marty Gras]

Many different ways to go, but for trouble free performance, please look at the facts. Most popular "oldtime turbo cams" are on 114 degree lobe centers, and today those who are doing marine turbo motors have gone (up) to 115 and more (non drag boat) for the lobe centers. "Holding cylinder pressure" is a critical equation when doing turbos and most people don't get it. Back in the '70's turbo motor builders were "worried about spooling up the blowers" and now we know that even the 'old turbos' don't really need to be "forced" up to speed. The other 'very critical' equation, is "back pressure, or the force needed to MAKE THE BOOST. We all know that horsepower is AIRFLOW. The motor is an air compressor, so why would anyone 'restrict' the exhaust flow? Many of the "older turbo cams" have a SMALLER timing/ lift event on the exhaust side of the cam timing. It just holds in unwanted heat and that point has been proven with the "new turbo cams", both in American and foreign engines. I have had an Engle TCS7 in my Chevy truck for just over 224,000 miles, it holds too much unwanted heat. It ran good, but just too hot. I will be going to a GM cam, .500 lift, .220 degrees @ .050" on both. Advanced 5/6 degrees. It's a 115 center cam and it will have an exhaust closing around zero degrees, which is what you want for a turbo motor. I've done quite a few winning 'ski race' turbo motors, 2 drag race turbo motors, lots of 'play turbo motors', and own a 461" work truck that has gone 498,000 miles with a turbo on it. I will never use a "restricted exhaust timing cam" ever again. They just run too hot! You may just have a stock GM cam anyway.

[Clearlake Kid]

Thanks for all the info guys.......It helps alot