stroked small blocks in the race cars?

[blykins]

You don't want to buy the next size up if they are 180cc.

A 180cc port is plenty big enough for a 289. My 347's make almost 550 hp with 185cc heads.

The goal in porting is to increase the velocity and flow, not make things bigger per se.

We can essentially make a port "huge" and it may not do anything but make the engine sluggish.

With that Dart head, there's not any reason why you shouldn't be making up over 475 hp. Camshafts have a lot to do with that and most guys tend to pick stuff out of the catalog, which is a big no-no. You end up with a Chevy cam. If you mean that your cam has 256° duration at .050" lift, then your engine should be making a ton of horsepower. My 289's with ported factory heads (200-210 cfm) make 440-450 hp with about 10° less duration than you and only .500" net lift at the valve.

[1795]

Thanks Brent,

That's what i needed to hear. Thanks, for correctly restating what I meant to type this morning, 256 degrees duration at 0.050" lift. I do want some more power to offset the added weight of the Dart Block. I also have read in my research what you stated regarding increased port size potentially having the effect of bogging the engine down. I just want to make sure that there is enough velocity and flow to provide the power at the upper end. Investing in a lightweight crank, rods and pistons so that the engine easily spins to 8,000 rpms is worthless if there is not enough air/fuel mixture to support it.

Hope that your family had a nice Christmas.

Now get back to work, you have engines to build

Jim

[blykins]

The block may be a bit heavier, but it will result in more horsepower due to thicker walls and better ring seal.

Remember that with a new block comes different challenges to flat tappet camshaft situations. The lifter bores won't be in the same place as your factory block.

[1795]

Thanks Brent. I have roller lifters so hopefully that will make it easier. This guy has been working on Ford engines primarily since the late 70's and has used some Dart blocks previously. He actually had one sitting in the shop for me to look at. He has already discussed some improvements to strengthen the valve train. Always appreciate all of your input.

Jim

[MAStuart]

Jim what is the top speed that you have run at any of the tracks your at?

[1795]

I probably will still limit my top rpms to around 7,000, but will set the rev limiter to closer to 8,000 just in case I am running out of rpms a little before a corner and do not want to throw another shift in before braking.

Top speed that I have done is about 135-140 mph. Not suer exactly as in prior years my camera did not have the ability to show speed. With the new camera with GPS I can get a more accurate speed. We will see this year. Mid Ohio has a nice long back straight so I should be approaching my top speed there. One of these days I will make it out to Road America and that will really allow for the opportunity to open the car up in 4th gear.

Jim

[MAStuart]

Brent I was checking out you internet site. But i did not get any of the answers to what i was looking for. I was wondering how well equipped your shop was. Do you do all your own machine work , crank grinding, boring, honing, balancing. ect. If so do you have all new state of the art machines?

[blykins]

Originally Posted by MAStuart

Brent I was checking out you internet site. But i did not get any of the answers to what i was looking for. I was wondering how well equipped your shop was. Do you do all your own machine work , crank grinding, boring, honing, balancing. ect. If so do you have all new state of the art machines?

Well, I think everything is up to date. Last year I upgraded from a yard stick to a tape measure and I bought one of those fancy pullin wrenches that have the little beams on the top.

[MAStuart]

Jim it has been a long time since i have run my mustang at Road America. I dont have much experience road racing. I have run in some open track events there. I ran in an full track autocross and got a 3 place. I was in a class with r model type shelbys and clones. Asked some of the other guys how fast they were going down the long downhill straight. Was told they were running 150-160. They were running 3.89 to 4.11 gears and turning 8000+. My car was limited to about 135 because of Rev limiter set at 6500 and 350 gear. Not sure i topped it out ever on the track because I am a chicken. My car i run a non overdrive 5 speed and I never got lower than third gear on that track.

[PDUB]

Originally Posted by blykins

You don't want to buy the next size up if they are 180cc.

A 180cc port is plenty big enough for a 289. My 347's make almost 550 hp with 185cc heads.

For clarity Brent, did you change head companies in your comparison, does Dart make both 180cc and 185cc, or was it just an errant finger on the number 5 key?


Either way, that is a nice, impressive number!