exhaust tuner

[rprinzo]

There are three different 2.5 200 Blocks that exist. The First was the 1991 F Block which was the first year for the 2.5. That Block came straight from the factory with a 7 petal front. It was only produced one year 1991. These are Extremely rare But well sought after. Then there are the other two blocks EE which is the Small Chest Block and the FF which is a Large Chest Block. So YES!!! There is a Difference And in taking either Block EE or FF to the next level The FF is the preferred block over the EE. In other words EE= ALOT OF WORK!!! FF = Much Less Work. The FF Block is the Preferred Block for Racers that want to Run in the Stock classes where mods by the rules are kept at a minimum. The FF 2.5 200 block and the NN 225 Pro max Block are similar in Chest configuration but the Port Timing it totally different.

So to say Its just Hype couldn't be further from the truth. They are coded for a reason because there are differences in Chest and Porting configurations. To fully understand the differences in the F, EE & FF Blocks one would need to have all three bare blocks in front of them to fully understand the differences.

A bit off topic but Its heard alot especially at the race tracks. Youll here Its a 300. Really meaning Its been Cut to 300 specs. but in reality its still a 260 thats been Modified and cut to 300 specs. But The Chest of a 260 and 300 Are totally different and a 260 can never have the same chest configuration as a Factory 300. It Can come close but thats it. Then there is Transfer/Boost Ports. They are also configured differently but Im not going to get into all of that.

If you really want to see the difference in a Factory 300 and a Cut 260 here it is.

Attachment 487819 Attachment 487820

Thats about as simple as i can put it in a Nut Shell.

now thats the info ive been lookin for.

heres a little background on me, played the HP car game for many years, then when my kid was old enough, spent 10 years racin 2 stroke karts being his wrench. but those were single piston italian 40hp motors that wernt allowed any mods other than boring. got to the level of stupid money(as in all racing),spent 3 years there and got out. at that level your just payin to be on a factory team and the fun is gone. so now i get to spend my money on me and this new game of HP v6's. so ive got a decent understanding of what your saying,so if you want to explain it all,your not wasting your breath,im absorbing every bit of it,and appreciate it. if ida known just what ive learned in this thread ida prolly looked for a promax to build,but ill save that for next time

[LakeFever]

X2 this is great info. You guys are talking me into promax'ifying my FF real quick here. Opening the chest and matching up the rectangle ports sounds easy enough, any dimensions on those or is it like head work just make em smooth and symetrical and open the window so to speak, straighten out the shot kinda thing.

[HStream1]

The web in the chest is the bad choke point (I dont have a picture) I dont have any stock Blocks . The Exit and entrance ports are already matched from the factory as Cast. But The Chest is where everything needs to start and go from there. Its a TON of Hand grinder work. A Milling machine makes life easier. Just need to angle the block 30degs on each bank when Hogging out the Chest web. Then its hand smoothing and polishing. I ceramic coat all my stuff. Preventing unwanted heat transfer ==== Horse power.

Im signing off for the Weekend Guys!! So everyone have a safe and happy Memorial Weekend!! And Please take a few minutes to remember why we celebtate it. A Person serving This country Died making sure we still have our remaining freedoms!!!

X2 this is great info. You guys are talking me into promax'ifying my FF real quick here. Opening the chest and matching up the rectangle ports sounds easy enough, any dimensions on those or is it like head work just make em smooth and symetrical and open the window so to speak, straighten out the shot kinda thing.

[LakeFever]

Does anyone know if the promax 200 block is the same as the 225 block? I’ve read the 200 is five petal and the 225 is seven but that’s about all I have seen mentioned.