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914World.com _ 914World Garage _ muffler question
Posted by: double-a Jan 9 2005, 07:21 PM
despite the custom "folgers can" hole patch, i think the muffler on the http://www.914world.com/bbs2/index.php?act=ST&f=2&t=21925&st=0 needs replacing. but before i go out and get one, i need a question answered.
i've heard on a couple occasions that "backdating" the entire exhaust system can add a nudge of hp to a 1.8. if this is true, what (if any) additional muffler options are opened up if i do this? and what roadblocks will i encounter? what component parts are necessary? thanks,
~a
p.s. restoring this car is turning out to be a lot of fun (aside from the persistent vacuum leak... grrrr), and i appreciate the mass knowledge of this forum, without which i would have learned and accomplished little. 
Posted by: Bleyseng Jan 9 2005, 07:42 PM
The 75/76 HE's suck big time with the J tube set up. Find a set of 1.7 or 2.0l SSI stainless steel HE's, proper hanger bracket and the muffler (Bursch is nice). Locate a complete set of proper tin and heat guides and voila! killer heat and 'mo power! plus the HE's don't rust away on ya.
Geoff
Posted by: ! Jan 9 2005, 08:47 PM
Backdating is mostly a 911 (engine) thing....it means using pre smog heat exchangers with equal lenght tues that use a dual in banana muffler.
Never heard it used on four bangers...but I assume that would mean the same....using the 73-74 style heat exchangers....either OEM or SSIs.....but you need the correct muffler hanger and muff....
Posted by: double-a Jan 9 2005, 09:41 PM
| QUOTE (Bleyseng @ Jan 9 2005, 05:42 PM) |
| The 75/76 HE's suck big time with the J tube set up. Find a set of 1.7 or 2.0l SSI stainless steel HE's, proper hanger bracket and the muffler (Bursch is nice). Locate a complete set of proper tin and heat guides and voila! killer heat and 'mo power! plus the HE's don't rust away on ya. Geoff |
being a relative noob here, i'm gonna ask what is probably some really dumb questions.
the j-tube comes from where on the engine? do i need an entire set of different engine tin? and why is that necessary?
| QUOTE |
| but you need the correct muffler hanger and muff.... |
that's why i wanted to figure out all this exchanger business first, don't want to have to get a new muffler later.
~a
Posted by: Mueller Jan 10 2005, 12:27 AM
| QUOTE (double-a @ Jan 9 2005, 06:21 PM) |
| despite the custom "folgers can" hole patch, i think the muffler on the http://www.914world.com/bbs2/index.php?act=ST&f=2&t=21925&st=0 needs replacing. but before i go out and get one, i need a question answered. i've heard on a couple occasions that "backdating" the entire exhaust system can add a nudge of hp to a 1.8. if this is true, what (if any) additional muffler options are opened up if i do this? and what roadblocks will i encounter? what component parts are necessary? thanks, ~a p.s. restoring this car is turning out to be a lot of fun (aside from the persistent vacuum leak... grrrr), and i appreciate the mass knowledge of this forum, without which i would have learned and accomplished little. |
do a search for something along the lines of
"heat exchanger AND Dave Darling"
he lists all of the parts needed....
supposedly going from the restrictive '75/'76 exhaust to the earlier setup can gain you from 5 to 8 hp.....it also gives you more options for mufflers and such
Posted by: Rhodes71/914 Jan 10 2005, 12:50 AM
| QUOTE |
| Locate a complete set of proper tin and heat guides and voila! |
I will be using my 1.7 H/E on my 75 2.0 motor and was not aware that I needed different tin, is this true?
Posted by: rhodyguy Jan 10 2005, 10:51 AM
the engine "tin" you will need are the pieces under the cylinders, on the drivers side the shifter will be below it. the earlier style (pre 75)attaches differently to the heat exchangers than the later. the j-tube connects to the s-shaped piece that runs from the fan shroud to the inlet of the h/e.
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Posted by: double-a Jan 10 2005, 10:59 AM
| QUOTE (Mueller @ Jan 9 2005, 10:27 PM) |
| do a search for something along the lines of "heat exchanger AND Dave Darling" he lists all of the parts needed.... supposedly going from the restrictive '75/'76 exhaust to the earlier setup can gain you from 5 to 8 hp.....it also gives you more options for mufflers and such |
how right you are, it's on http://www.914world.com/bbs2/index.php?act=ST&f=2&t=22093&hl=heat+exchanger:
************************
To use the 2.0 heat exchangers (or SSIs) on a 75-76 914 (either 1.8 or 2.0), you will need:
The 2.0 exchangers
The 2.0 muffler
The 2.0 muffler hanger
2 muffler gaskets
4 2.0 exhaust gaskets (the copper rings)
8 exhaust nuts (usually best to replace them)
All of the heater hardware except for some hoses. That means--
2 S-shaped ducts from the fan shroud to the exchangers
2 J-shaped tubes from the large holes in the engine tin to the S-ducts
2 Extension pipes from the exchangers to the flapper valves
2 Flapper valves
2 Hoses from the flapper valves to the heater channels in the chassis
You can actually use the 75-76 flapper valves and the hoses; but the flappers can be a real pain to remove from the late exchangers (or the early extension pipes), and the hoses often need to be replaced anyway.
If you don't get the heater hardware, the exhaust will still function--but the heat won't.
************************
seems like a lot of parts, so where's the best place to get all this stuff at once? i could buy the parts piecemeal, but would rather get it all in one place.
~a
Posted by: double-a Jan 10 2005, 10:59 AM
| QUOTE (rhodyguy @ Jan 10 2005, 08:51 AM) |
| the engine "tin" you will need are the pieces under the cylinders, on the drivers side the shifter will be below it. the earlier style (pre 75)attaches differently to the heat exchangers than the later. the j-tube connects to the s-shaped piece that runs from the fan shroud to the inlet of the h/e. |
ahhh, thank you. that explains a lot i think.
~a
Posted by: rhodyguy Jan 10 2005, 10:59 AM
so when you have the aux fan in the engine compartment running, it helps to push air through while the fan on the engine is spinning at lower rpm. the air comes out the other side of the h/e, to branch tube, to belows, to flex tube, to inlet on the fire wall.
kevin
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Posted by: rhodyguy Jan 10 2005, 11:01 AM
what par of my reply was unclear?
kevin
Posted by: rdauenhauer Jan 10 2005, 11:14 AM
Great Pic's Kev. Makes perfect sense to me! 
Posted by: rhodyguy Jan 10 2005, 11:16 AM
and to further confuse the issue, the shift rod runs under the tin piece for a sideshift trans. the shift rod runs on top of the tin in a tailshift trans. 
. so to do the conversion in your car, you need the tin off of a 73-74.
kevin
Posted by: double-a Jan 10 2005, 12:06 PM
| QUOTE (rhodyguy @ Jan 10 2005, 09:16 AM) |
| and to further confuse the issue, the shift rod runs under the tin piece for a sideshift trans. the shift rod runs on top of the tin in a tailshift trans. . so to do the conversion in your car, you need the tin off of a 73-74. kevin |
but just the tin under the engine, correct?
~a
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