I have.....I think there is a thread where 9K posted some pictures of it...I can answer questions if you want


LOL...just looked..it's in this thread

 

No idea, but I have some data logs that include EGT from last June. I have a track day this Saturday and can log it again for comparison. I was running an OEM cat last year and am running a BHR midpipe this year. I don't have a prediction for what any difference might be. And, while the weather conditions should be similar, it is a different track, so direct comparison will not be possible.

The main features of a catless midpipe are the fact that it won't clog and that it isn't pushing hot backpressure against the engine. Or at least IMHO. The only reason I bought mine is for its potential to add some long-term reliability to the system.

 

I am guessing that midpipe would lower EGTs, help engine run cooler = better timing and reduce transmission temperatures- stock cat is a heat trap

 

Actually I think it will make the transmission hotter if the car is sitting with the engine running as it removes a bunch of heat shielding. On the other hand, once the engine is switched off, there is much less thermal energy to transfer out of the pipe compared to the cat, so the car will cool off faster

I'm not sure what it will do for EGT. Lower at speed due to less backpressure? Less thermal mass so it will change quicker, and heat up more when you get on the throttle?

EDIT: but what does this have to do with diff temps? :-P

 

^ So you are NOT interested in my EGT comparison then? :P

Yeah. Should probably start a new thread instead of continuing to hijack this one.

 

Duh... I'm pretty stupid

 

Not at all. I have a photographic memory for visual, but if you tell me something I can't remember what it was 3 minutes later.

Did you ever buy the aftermarket rear cover?

 

No I didn't go with the aftermarket rear cover. I think the S2 rear cover plus a diff cooler should be more than sufficient. My diff has been holding up ok with no cooler but it does get SUPER hot an recently started to leak quite a bit. Plus I might be doing some longer races next year. No sure if the transmission needs cooling yet...

 

If you are going to go through the trouble to do one...you might as well do them both

 

Seems to me the transmission gets hotter than the diff, although I have not actually measured either.

 

If you're doing a cooler, then why bother with an S2 cover as well? I thought the only supposed benefit was a slight improvement in cooling, but the external cooler takes care of that, so there's really little to no benefit for the added cost, as far as I can see anyway.

 

In my situation the Diff was markedly hotter than the Tranny

The tranny didn't tend to get much over 280 degrees.....the Diff on the other hand was usually over mid 300's. I remember talking to some of the GrandAm racers when they were running the cars in ST...and they said the same thing..tranny was OK...but the Diffs got super hot

 

You have to modify the cover to do it properly...so if you need to get another one anyway...might as well get the S2 one Personally I would just re-use the one I took off...but it isn't my daily driver

 

With healthy stock OEM cat:



With BHR midpipe:



Basically no difference.

/hijack

 

No hijack, just validation ...

 

I was pondering about in which situations a cat delete would lower EGTs.. I couldn't come up with any scenario that would significantly reduce it.

 

on average 30F reduction which is not much (less than 2%), however that can be viewed differently if you made 10 more HP and still been able to operate at the slightly reduced EGTs

what about coolant temps, and timing for those two scenarios?

can you detail the differences with your car set up and the track conditions between the 2 scenarios?

were you running the same tune?

 

I'll order up some more RCHs before we run out ....

 

Nice charts. They are close enough to say it is the same. The max temps are identical. The average temp diff of <2% might also be explained by the longer period of idle at the start of the BHR midpipe run.

 

Yeah. The listed average temps are useless as the data are not normalized The true average looks to be very close to the same at a little over 1650F.