formula1

I've been pricing aftermarket exhaust for my '90 F 292 SR 1 with 454 mags & Bravos. I keep being asked if I have a "standard opening" for the exhaust to exit thru to the transom? Please help, I don't know for sure. Also, most seem to require their own "tailpipes" to finish the application. Any thing I should know for those as well? Last, I can't remember if I need an ignition mounting bracket, too. Sorry ya'll, I can't check myself because the boat is three levels up in a secure dry storage facility!

t500hps

I just pulled 2 complete sets of Stainless Marine exhaust off an 1989 F272 SR1(454's) that have the standard bravo riser and throttle brackets. Turns out my Formula 312 needs the 3 inch taller risers and these won't work. I'm looking for replacement risers only unless someone wants the entire package I have.....then I can get the right stuff for my application.
Anyway, get the manifolds and risers with the throttle and ignition brackets and use rubber hose to complete the run to the transom....that is what Formula did with your setup originally. (standard openings too)

anyone else verify these details???

RedDog382

The thru-hull transom openings are not "standard" on Silent Thunder applications. They are about 3" higher than the standard Bravo openings. Went through all kinds of problems with aftermarket exhaust on my '89 311.

3" rise CMI headers will not fit due to clearance with the fiberglass deck. Standard rise CMI's need custom tails that are almost vertical causing significant reversion.

Best combination I had was Gil manifolds with custom tails, but I don't think they are in business anymore.

Finally solved my reversion problems by trading to a 382 with semi-dry tails that dump water outside the transom.

offthefront

pretty much what Dog sez ..... I have the Gil manifolds and Stainless Marine pipes ...pipes were made for a tranny setup and thus extend into the transom ... like 3/4" from going all the way thru ... I put blue hose and the rubber flappers (glued) on the hose ...has worked well ...I too really like the pipes that dump the water at the end of the pipe instead of up near the motor .....m

http://www.gilmarine.com/products/exsys/dosystem.html

http://www.offshoreonly.com/forums/s...ad.php?t=90236

formula1

t500hps, got any pics of that exhaust setup? That might be exactly what I am looking for! How much do you want for the set ups? Also, how much use do they have?

mtgbiker

CMI E-Top pipes will work in a 292SR-1. I have a 89' 272SR-1 with re-worked 454/420hp's. The 311SR-1 is a TRS set-up and has different centerline dimensions than the 272/292 Bravo set-up. I have plenty of room under the hatch and more than a 4" horizontal drop to the transome tips. Plus CMI tails dump the water at the very end of the tails to prevent reversion.

I just installed my pipes last week. Be sure you tell CMI that the measurements for the tail pipes are from inside the bilge. CMI wants measurements from outside the boat. However, if you have the silent thunder platform, you can't get to the thru-hull tips without taking off the platform!

The following measurements are for a 272 SR-1 from inside the bilge along the transom:
The horizontal center of each thru transom tip is 12.875" above the centerline of the output shafts. The inside tips exit 13" away from vertical center of output shafts and the outside tips are 12" from center of shaft. In other words, the outside tails angle in 1".
The motors have a 34.5" crankshaft centerline.

Any questions, call fred cecil at Trick Marine #866-921-4553.








Make damn sure you tell your CMI dealer that the measurements are from inside the boat and they write it down on the built sheet, otherwise you will be waiting for them to be modified like me.

RedDog382

Is this with silent thunder application?

If it is, 4" downslope seems generous.

Unless you have a very mild cam, I will be surprised if you do not have reversion problems.

Only speaking from my very extensive personal experience.

RedDog382

Not mine. Bravo package on the '89.

offthefront

mtgbiker ....that is some very good information ..the dimensions your quoting are for the 272 ? If so I would think my 311 would be similar. I was planning to modify my silent Thunder so the exhaust exit without the sound box ... I had planned to eliminate everthing below the platform itself ..I would leave the outer supports. If you notice the outside exhaust actually go thru the transom inside the outer part of the box ( toward the drives) and then the box angles the exhaust out. My problem is that the stock holes are too high. I think they would need to be lowered but I wasn't quite sure exactly they need to be . And if I do the mods it was mean new exhaust or at least pipes ... I want to retain the look of the 311 from the side.. m

Oh and Dogs correct 89's (most if not all) are Bravo ..

formula1

Thanks for all the info! I want to keep the silent thunder platform...I think it really adds to the classic lines of the older Formula design!

I really like the looks of the CMI's and the perfromance claims seem to be realistic since they are the only tubular designed header we are talking about here. But, the cost seems a little steep for me now.

Maybe Gil's, Eddie's, Rev's or the new Dana Marine setups.