Let's talk 3.2SS and EFI

[msmall215]

You might be rolling your eyes saying "Not another 3.2SS thread," and yes I have used the search function and combed through pages of 3.2SS threads, some new, some old.

I'm beginning to research and plan where I will go with my motor when the time comes for a rebuild and 98% set on 3.2SS for a number of reasons. Car is an '83 SC Euro/RoW with the 930/10 engine (9:8:1 comp, large port). Use is 85% street, 15% track use, so a good wide torque band is paramount, and I'm perfectly happy to sacrifice a few ponies at the very top of the power band. The engine is internally stock with Triumph ITBs (42mm tapered down to 39mm at head) and AEM ECU, SSIs, and a trick muffler resulting in 200.4 hp and 187 lb ft of torque at the wheels. Pretty respectable for a mild 3.0.

In all the threads I've read, I haven't seen too many running a 3.2SS with EFI, and piston offerings have changed throughout the years, so here is where I turn to the Pelican brainchild with a few questions in regards to what is available on the market today, etc. I would of course retain EFI and possibly change to larger throttle bodies depending on the final configuration, so I'm not limited by cam choice.

1. I know the old Max Moritz 3.2 kit was designed to be used with CIS and had wedge shaped pistons as such, with I believe 9:8:1 compression. Are there piston sets out there these days for use with non-CIS (read, had relief cuts) that lend themselves to a single plug setup?

2. Given a piston with cuts and the ability to breath, combined with ITBs, what are some general cam recommendations to deliver good torque down low?

3. Any benefits to utilizing 3.2 cylinders vs 3.0 cylinders? (both bored to 98mm and replated)

4. Worth it to port the SC heads or just opt for 3.2? Alternatively, if I leave them as is, knowing they're the larger ports, am I really missing out?

Finally, the curveball, going 3.4 on the 3.0 case is at the back of mind...3.2 cylinders, crank, rods, etc. Anybody done this and care to chime in?

Looking forward to input from the community, and here's a pic of the car because frankly no one likes pictureless threads

[trond]

if going 98 mm and focus is torque and upper midrange I would stay with SC heads.
3.2 cylinders can be bored out to 98 mm but SC cylinders with ring gasket groove are less suited

I have 98 mm, small port heads and stock cams. Triumph ITBs waiting on the shelf. I imagine i have less than 200 rwhp but engine is faster than suspension and feels strong in the RPM range I use on the road. Pulls great from low down but not much point in going above 5000 rpm. I believe my engine has a better torque delivery in the bottom end of the register than many that go with hot cams

[Nux]

I have the original 3.2ss MM kit. It is 9.3:1 whereas the 3.4ss version was 9.8:1. I also have big bore heads (39mm) and Triumph ITBs.

If you choose the wedge shaped pistons, you'll be limited to DC20 or maybe 993ss cams as these pistons do not have valve pockets.

I have DC20 in mine and they work very well but must be timed to 1.8 to clear the pistons. You can use 964 cams without any issues.

The general consensus is that the SC cylinders are not well suited for the 98mm bore and you should either use 3.2 cylinders or buy a complete new set of p/c. Some choose to bore the SC cylinders anyway though.

You can have any piston made to accomodate hotter cams as long as you keep the CR below 9.8 - or go twin plug.

The ss engine is lovely and the rev happy nature really is nice with cams that move the powerband a little up.

I would definitely port the heads.

You should consider just swapping the pistons for 10.5cr and twin plug your heads. Cost about the same as big bore single plug. My last build like this had 310nm torque at 5000rpm and 260 already from 3000rpm. Thats Better than a 3.6 mind you.

[Litle brother]

My 3.2 SS makes 247ft.lbf and 290PS.
39mm intake heads
10.3:1 98mm Mahle RSR p/c's
Webcam 120/104
Twin plugg
46mm PMO itb's
Full sequential ECU.
39mm Eisenmann primaries and modified Eisenmann muffler.



Sent from my iPad using Tapatalk

[chrisbalich]

Originally Posted by msmall215

1. I know the old Max Moritz 3.2 kit was designed to be used with CIS and had wedge shaped pistons as such, with I believe 9:8:1 compression. Are there piston sets out there these days for use with non-CIS (read, had relief cuts) that lend themselves to a single plug setup?

2. Given a piston with cuts and the ability to breath, combined with ITBs, what are some general cam recommendations to deliver good torque down low?

3. Any benefits to utilizing 3.2 cylinders vs 3.0 cylinders? (both bored to 98mm and replated)

4. Worth it to port the SC heads or just opt for 3.2? Alternatively, if I leave them as is, knowing they're the larger ports, am I really missing out?

1. The need for twin-plugs is to overcome incomplete burn due to the piston dome reaching 'squish' before the flame front moves across the whole cylinder. If you want to stay single-plug, just keep the compression at or below 9.5:1. No need for a specialized piston.

2. If you want to focus on low-rev torque, stay with cams like the DC19 or 964. The hotter the cams, the further up the rev-range you have to go to make power.

3. The CE ring is the limiting factor. If you want to live more on the edge, hog out the 3.0 jugs. If you want to play it more conservatively (like most on here would do), get some 3.2 jugs and have those hogged out.

*there is a thread on here somewhere where 97mm P&Cs are being offered for about what it'd cost to buy pistons and have cylinders remanufactured.

4. Again, if your focus is low-rev power, keep the SC heads. The smaller ports will generate greater port velocity and subsequently more torque. I would keep the Triumph ITBs until the build was complete and see if you need more breath to reach your goals. I think you'd be pleasantly surprised with how much air they can move.

[msmall215]

Originally Posted by chrisbalich

1. The need for twin-plugs is to overcome incomplete burn due to the piston dome reaching 'squish' before the flame front moves across the whole cylinder. If you want to stay single-plug, just keep the compression at or below 9.5:1. No need for a specialized piston.

2. If you want to focus on low-rev torque, stay with cams like the DC19 or 964. The hotter the cams, the further up the rev-range you have to go to make power.

3. The CE ring is the limiting factor. If you want to live more on the edge, hog out the 3.0 jugs. If you want to play it more conservatively (like most on here would do), get some 3.2 jugs and have those hogged out.

*there is a thread on here somewhere where 97mm P&Cs are being offered for about what it'd cost to buy pistons and have cylinders remanufactured.

4. Again, if your focus is low-rev power, keep the SC heads. The smaller ports will generate greater port velocity and subsequently more torque. I would keep the Triumph ITBs until the build was complete and see if you need more breath to reach your goals. I think you'd be pleasantly surprised with how much air they can move.

Some great points here and above to consider. I saw Henry's 97mm set and have been considering it as the actual displacement is very close to 3.2 (a hair under vs Henry's kit with a hair over 3.1) and it's a hell of a deal for a new set of P/Cs, rings, etc. As far as twin plugging goes, I have access to 93 octane here in PA, but the car does spend some time in CA almost yearly. The benefits of easier starting and the ability to maintain performance with 91 octane would be nice instead of shoving octane booster in every tank, but I realize it's all part of the larger equation.

[Jonny042]

Originally Posted by msmall215

Looking forward to input from the community, and here's a pic of the car because frankly no one likes pictureless threads

That's a great looking car.

The only input I have is that the 39mm ports, and 42mm throttles, is a pretty nicely matched intake system. If you're making good power already with the 3.0 with stock internals, a set of 98mm JE pistons, some mod-s cams or something a touch hotter (talk to Camgrinder, but maybe some DC43-102's..... which was my choice for my 3.2SS). Should give you a nice bump in power I'm hoping for 255-265hp on my MFI build which has similarly sized intake tract.

[chrisbalich]

Originally Posted by Jonny042

That's a great looking car.

The only input I have is that the 39mm ports, and 42mm throttles, is a pretty nicely matched intake system. If you're making good power already with the 3.0 with stock internals, a set of 98mm JE pistons, some mod-s cams or something a touch hotter (talk to Camgrinder, but maybe some DC43-102's..... which was my choice for my 3.2SS). Should give you a nice bump in power I'm hoping for 255-265hp on my MFI build which has similarly sized intake tract.

While John is very knowledgeable, I would call Web Cams or Elgin were I to do it again.
Either of you can PM me if you want more details.