3.3 CIS upgrade thoughts
 

Unexpectedly needed to fix broken head studs <sigh> and so decided to split the case. Now wondering whether there are any additional "bang for the buck" mods to consider. Just a strong reliable street rod, not my race/track car. Budget is tight but now's the time to consider options since she's out and laid bare. Unfortunately it's been so long, I've lost track of costs and not been up on the latest trends. i.e. would a 964 cam grind be worth it (~$2K)? Twin plug ($3k?), port intake ($500?), head porting ($1500?)?, etc., etc...?

Current build = stock '83 3.3 CIS except for:

• Gasketed heads
• Euro fuel feed with IA mod'd fuel head
• BLeask WUR
• Kokeln Intercooler
• B&B headers & custom twin outlet muffler
• IA K27S Turbo
• Tial 46 WG @ 1.0 bar
• 964 BOV
• RUF intake plenum, cone filter
• G-50/03 short trans

Thanks in advance for input!

If you've got it all apart, why not? When is the next time you'll have it all apart again? You do all these upgrades and maybe you wont have it all apart for another 10 years. I think you could find 964 cams for under $2k.

Can your cams be re-ground to 964 spec?
Elgin did my stock cams to their Turbo S grind. You'll need to have the rockers done, about $500
Turbocraft did the valve job, ported the heads, match port the aluminum injector blocks and intake manifold. Around $2500-3000.
If your having the heads done, it shouldn't be that expensive to add a second plug hole. Also not sure if needed if you stay with the 3.3
These are prices from a few years back, so best to confirm.
Also send the injectors out for clean & test
You may want to add the BLeask rpm switch
I used a Electromotive xdi controller which can be set up as single or dual plug.
Fun stuff.

my 2 cents if all you want is a reliable and fast street ride, not another race car:

- you do not need the twin plugs and doubling up the harness, etc. for a 3.3liter or even larger.
- I had the K27s and swapped for GT35 and I noticed a difference. I really like the GT35 turbo. I did not think the K27s really provided as much fun.
- I have not swapped cams and I can burn the tires all through first, in second, no lack of get up and go. So, I have to assume better cams will be even more fun. TK has some new cams that are supposed to be better than SC or 964 but cost a lot more. Either those or SC or 964.
- get a limited slip diff installed
- get a bigger intercooler if not already upgraded (I cannot see your post while in this edit window...)
- put the rest into suspension, brake pads, alignment, and tuning the CIS unless you can swing EFI

good luck. fun to have these kinds of decisions to make :)

What was the difference between the k27 vs the gt35?

Thank you all very much for your much appreciated input.

Going with the porting and now researching cam regrind options.

Sticking with K27S for now as I like it's linearity. The Kokeln mod'd Garrett it replaced was real peaky (dramatically so! ;-) though I understand the GT35 is better behaved. The split plenum header design has me interested for perhaps the future.

The G50/03 has LSD and I upgraded the suspension first thing with upsized gun-drilled T-bars, Elephant Racing adjustable spring plates & sway bars and then of course big red brakes.

My 2 cents; you should do cams; 930 cams are really soft. SC cams will wake the car up. SC cams make the most low/mid-range (eg off-boost) torque; 964 cams sacrifice a little of that for slightly more top-end. But unless it's a track car and you're Walter Rohl, you'll spend >95% of your time off-boost anyway. And as it's forced induction, you can always get that 10HP at the very top.

Should be able to get cams reground for ~$500. Or buy SC/3.2 cams (either - same profile) and machine in the scavenge pump drive.

I'd twin-plug while the heads/covers are off; pretty cheap, can hook it up anytime - and once you do, it can improve low/mid range running and improve pickup & add a margin of safety.

ARP rod bolts while it's apart; factory ones are known weak- and a dropped rod bolt is a PITA. ARP bolts are also re-usable. Pauter rods come with them - just sayin'....

Supertec head studs; work great, supposed to be better metallurgy than any of the factory studs, cheaper. I've been running mine since 2007.

I was very, very, happy with my K27/HF with CIS - linear, predictable, lots of urge, lasted very well. Perhaps this would be an upgrade from the K27/S for you?

Last, but not least - RarlyL8 headers. The craftsmanship is a work of art, and they're just obviously a better design than BB/GHL/Fabspeed. Heat's no better though - I'm anxiously awaiting Classic Retrofit's electric heater :)

You could flow the pancake slightly. But if you start porting too much, you'll likely find a whole bunch of other things should be done as well to keep everything balanced...

And there's nothing worse than getting it all back together and then realizing "doh! I should have done X & Y ..."

After considered porting, high compression, bigger displacement, rods, studs etc etc etc on my car life has thrown me a curve and I'm in a roughly similar place except my stock studs are fine, so I'm not touching them until one breaks.

I've already got RalryL8 exhaust, K27/29, TK long neck and using the FrankenCIS for mixture control and its working well.

I've decided to go with SC cams, refurbing my rockers, lightweight clutch package. But because I've already got a microsquirt managing my mixture for me instead of the old school Rube Goldberg Leask WUR and rpm limter I'm going to leverage the microsquirt for a wasted spark ignition setup with COPs and be able to fully control my ignition as well. I think that will give a pretty good bang for the buck without pistons, cylinders, porting, twin plugging. I'll wait on that will a head stud lets loose :-)

Hey pdqcarrara,
I’ve got a pair of 964 cams that I’d let go for $650
The cams are pristine. The car they came out of had 40k at the time of removal.
John Doughrty made the appropriate mods for use in our 930 motors.
Shoot me a pm if you’re interested.
-Paul