964 Engine rebuild
10-23-2013, 04:46 AM
#121
Racer
Thread Starter
My magnesium valve covers are letting a bit through and I don't know whether it is because they are warped or whether it is the RSR rocker arm o-ring seals that I fitted and was never 100% sure about. Either way it will be sorted next time the oil is changed/tappets done & I'll report back.
As far as the famous head gasket debate goes. Who knows. There are some very clever people who know these engines inside out who argue the case either way.
On another note I'm now a professional window fitter and have a nice view of erm, not a lot really but I'm £120 richer as you said! Just got to get a longer piece of flexi pipe for the dizzy vent to finish it off.
10-23-2013, 09:28 AM
#124
Racer
Thread Starter
The MAF kit is an Autothority. All of these kits tend to have their lovers and haters but so far I haven't got any complaints.
My engine wouldn't run right with my original 'barn door' AFM, I tried swapping it with a friends AFM and it still didn't run right so I tried changing it for this Autothority with the chip that came with it and it still wouldn't run very well but was better so I left it in until I drove it up to Wayne Schofields old place where he made a custom chip for the engine with it on.
Just thinking out loud, I don't really like the 'barn door' AFMs a lot and think they're a pretty dated arrangment (do any modern cars still run them?).
I think they changed to a 'hot wire' system on 993 engines so I don't know whether there is any mileage in trying to transplant one of these onto a 964 engine?
May not be possible or may have already been done.
10-23-2013, 02:29 PM
#125
Burning Brakes
The MAF kit is an Autothority. All of these kits tend to have their lovers and haters but so far I haven't got any complaints.
My engine wouldn't run right with my original 'barn door' AFM, I tried swapping it with a friends AFM and it still didn't run right so I tried changing it for this Autothority with the chip that came with it and it still wouldn't run very well but was better so I left it in until I drove it up to Wayne Schofields old place where he made a custom chip for the engine with it on.
Just thinking out loud, I don't really like the 'barn door' AFMs a lot and think they're a pretty dated arrangment (do any modern cars still run them?).
I think they changed to a 'hot wire' system on 993 engines so I don't know whether there is any mileage in trying to transplant one of these onto a 964 engine?
May not be possible or may have already been done.[/QUOTE]
Cheers Alex thanks for the info. I think the MAF have several advantages the cost of production, less weight and faster response. I will look at installing one but it will require the chip modifying by Wayne as you did and also some wiring mods as the connections are different. Rob
My engine wouldn't run right with my original 'barn door' AFM, I tried swapping it with a friends AFM and it still didn't run right so I tried changing it for this Autothority with the chip that came with it and it still wouldn't run very well but was better so I left it in until I drove it up to Wayne Schofields old place where he made a custom chip for the engine with it on.
Just thinking out loud, I don't really like the 'barn door' AFMs a lot and think they're a pretty dated arrangment (do any modern cars still run them?).
I think they changed to a 'hot wire' system on 993 engines so I don't know whether there is any mileage in trying to transplant one of these onto a 964 engine?
May not be possible or may have already been done.[/QUOTE]
Cheers Alex thanks for the info. I think the MAF have several advantages the cost of production, less weight and faster response. I will look at installing one but it will require the chip modifying by Wayne as you did and also some wiring mods as the connections are different. Rob
12-15-2013, 07:19 AM
#126
Racer
Thread Starter
Exhaust diameters / 993 heat exchangers?
I'm interested in the fact that you chose 1 3/4" headers rather than 1 5/8" for this build.
If I remember correctly, Gamroth/Weiner will be using the narrower headers for my build this winter...if I'm not wrong, they have a reason for doing so and I'll have to ask.
Chris, when we do the RSR build (probably two winters from today, sadly, but I can't handle 370hp yet) the current tranny is yours should you want it, tehe, as I plan to go six speed.
If I remember correctly, Gamroth/Weiner will be using the narrower headers for my build this winter...if I'm not wrong, they have a reason for doing so and I'll have to ask.
Chris, when we do the RSR build (probably two winters from today, sadly, but I can't handle 370hp yet) the current tranny is yours should you want it, tehe, as I plan to go six speed.
I might also have a go at a new silencer to give me a few more options.
Final reason is that it's a pretty chilly place to be this time of year and I don't want a bit of cold to stop me using the car so may add a bit of simple heat back to the car. I must be getting soft in my old age!
The obvious headers / heat exchangers option is to use 993 ones with the flanges flipped and they have been proven to give very good power figures on some cars. I've borrowed a set to use as a template (cheers Jev) but having a measure the primary pipe internal dia is approx 1.5" and the outside diameter is approx 1.6".
My current headers while being cheap and cheerful with poor merge collectors (of a sort) have 1.75" internal dia and approx 2" outside diameter. Headers shown below and Magnaflow silencer shown in link.
https://rennlist.com/forums/9070634-post78.html
This is quite a size step down which bothers me a bit and if it won't allow the engine to breath properly then maybe it's not the way forward. I always thought as a rule of thumb that 1.625" was the 'norm' for a 964 and maybe 1.75" for 3.8 or tuned cars which is why I'm a little surprised that 993's have 1.5" bores.
I realise that changing the exhaust will require a remap but am clearly reluctant to do the work and make the change if I end up losing power/torque.
Can anyone who knows anything about exhausts offer any advice?
12-15-2013, 01:55 PM
#127
Three Wheelin'
I can't offer any direct help but having played with numerous exhaust setups on 4 pot (Caterham) engines, the dyno doesn't always show what you hope/expect. In some instances, too large a bore actually had a markedly negative effect. The length of the primaries (which tended to have a far greater effect on the performance on these engines) the diameter, the cam and it's timing are all functions of the same equation. They're all very much interlinked.
Looks great tho
Looks great tho
The following users liked this post:
kos11-12 (03-07-2021)
02-16-2014, 05:44 AM
#128
Racer
Thread Starter
OK, I've decided to make a new exhaust so found a suitable donor and been busy adapting it to fit the car and onto a set of 993 heat exchangers with flipped flanges. I did start looking at making up a set of headers and started to draw them but even with a mate welding them up they would work out very expensive and one of the main aims of this exhaust project is to keep it cheap!
I am still a bit worried about dropping primary tube dia from 1.75" bore to 1.5" bore and I know it will need to be remapped but I guess if it was good enough for the 993 factory cup cars.....
The aim at the end of it is to end up with someting vaguely resembling some of the arrangements below:
993 Factory Cup setup
Supersprint 993 setup:
Mega-money Kline system:
So here's the donor exhaust:
All pipes removed and the boxes needed shortening:
Out of the pipework, make an 'X' pipe to go from the inlet to the boxes so the end setup will look a bit like this:
Get 'X' pipe welded up and tacked onto boxes for a trial fit:
Popped the rear bumper back on to make sure it all fitted. Hopefully it will really help with ground clearance as it doesn't sit nearly as low and 993 h/e also hang a lot lower:
Finally for now made up a couple of lambda bosses but I'm not sure if there is a correct or optimal place to fit them or does it not matter?
I am still a bit worried about dropping primary tube dia from 1.75" bore to 1.5" bore and I know it will need to be remapped but I guess if it was good enough for the 993 factory cup cars.....
The aim at the end of it is to end up with someting vaguely resembling some of the arrangements below:
993 Factory Cup setup
Supersprint 993 setup:
Mega-money Kline system:
So here's the donor exhaust:
All pipes removed and the boxes needed shortening:
Out of the pipework, make an 'X' pipe to go from the inlet to the boxes so the end setup will look a bit like this:
Get 'X' pipe welded up and tacked onto boxes for a trial fit:
Popped the rear bumper back on to make sure it all fitted. Hopefully it will really help with ground clearance as it doesn't sit nearly as low and 993 h/e also hang a lot lower:
Finally for now made up a couple of lambda bosses but I'm not sure if there is a correct or optimal place to fit them or does it not matter?
02-16-2014, 02:25 PM
#133
Technical Guru
Rennlist Member
Rennlist Member
