thesnowdrift Posted 5March, 2013 Report Share Posted 5March, 2013 Ok so headers it is... Question is 1 1/2 or 1 5/8? Has any one got any advice? Will probably be going with twin outlet muffler aswell... Cheers Pete Link to comment Share on other sites More sharing options...
SteamWolf Posted 6March, 2013 Report Share Posted 6March, 2013 From what I have read, changing manifolds from 3.0L onwards is a WOFTAM. The old log manifolds are no good but the later style works well and aftermarket seems to offer no additional power. If anything, the 3.2 style means it is easier to run twin pipes but Iwouldn't bother changing from stock. Just change the muffler. Link to comment Share on other sites More sharing options...
Harvs11 Posted 6March, 2013 Report Share Posted 6March, 2013 From my basic understanding of exhausts and experience on V8's, a smaller dia. header gives a bit more back pressure which helps low rpm torque. Bigger dia. pipes help with WOT high rpm power delivery at the expense of low rpm torque. A 2 outlet muffler could also reduce backpressure. The type of drivng you do shoud influence the header/muffler choice. ie street=torque, track=WOT power Your 76 Targa is a 2.7 running CIS (?) I think these are sensitive to back pressure changes. Any one out there with some first hand real world knowledge might confirm/deny/explain this better than me. Link to comment Share on other sites More sharing options...
thesnowdrift Posted 6March, 2013 Author Report Share Posted 6March, 2013 From my basic understanding of exhausts and experience on V8's, a smaller dia. header gives a bit more back pressure which helps low rpm torque. Bigger dia. pipes help with WOT high rpm power delivery at the expense of low rpm torque. A 2 outlet muffler could also reduce backpressure. The type of drivng you do shoud influence the header/muffler choice. ie street=torque, track=WOT power Your 76 Targa is a 2.7 running CIS (?) I think these are sensitive to back pressure changes. Any one out there with some first hand real world knowledge might confirm/deny/explain this better than me. Exactly right Harvs... 2.7 with CIS, and only to aware of back pressure in it... I have slowly turned it into a comfortable street car that could easily perfom in the odd HillClimb... The old heat exchangers have to go as the entire heating system is now in the parts box... Smaller pipes may be the go... Does anyone know or actually had the physical experience at running either pipes after heat exchangers... Cheers Link to comment Share on other sites More sharing options...
Doish13 Posted 19April, 2013 Report Share Posted 19April, 2013 I've just spent 30 mins looking up info on exhausts. What I've learnt is hat SSI's are a great product however it will or may not increase the exhaust note of my car plus as the company was taken over by Dansk, the price of hese units have gone up. I've learnt if I just want to increase note you can hrough a new muffler and a set of SSi's. So question is if my factory heat exchanger units are not needing repair why would i change as I should be able to pick one up easily.(sports muffler) and achieve the same result? Is that correct or have I missed something? Also learnt about the Gundo Hack.... Anyone try it? Does it work? Sounds a bit rough... Link to comment Share on other sites More sharing options...
Vas Posted 19April, 2013 Report Share Posted 19April, 2013 Doish, you answered your own question. Just do the muffler. Link to comment Share on other sites More sharing options...
Doish13 Posted 20April, 2013 Report Share Posted 20April, 2013 I must have written that post half asleep as it made very little sense and full of typos. Thanks Vas. Link to comment Share on other sites More sharing options...
SteveT Posted 20April, 2013 Report Share Posted 20April, 2013 A good friend who is an exceptional mechanic once told me that back pressure is bad, not good. You don't actually want anything to impede the exhaust gases coming out through the exhaust system. Sure tuned length headers are good as each cylinders exhaust gets the same time to get away and the length of tube can give better results and performance at different rev ranges. So he said, made sense to me! Link to comment Share on other sites More sharing options...
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