930 turbo questions more power
 

I just purchased a 79 930 turbo with low miles and around 10,000 on a new motor. p.o. spun it in the rain and motor go boom:eek:

im not new to porsche just to the turbo. im looking at removing the reactors and maybe upgrading to a kkk27 and a bit larger intercooler. is this worth the money im looking for a bit more power.

also i found a manual boost controler in the engine bay that is hooked to the wastgate, the car makes .8 bar of boost and no more. not messing with it yet:confused:

i have read through alot of threads and could probably find my awnsers in time but would like to get some fresh ideas on what is the best mods for the car the will be safe.

i.e how much extra boost if any? a turbo that spools at a lower r.p.m.?

ok i wait for the knowledge to roll in

thanks ed
http://forums.pelicanparts.com/uploa...1217397155.jpg

You are on a very slippery slope as one thing leads to another. Free up the exhaust, then add more fuel, the add cams and a bigger turbo and intercooler. While you're in there, you might as well get bigger P&Cs. Oh then you might as well go EFI... Have fun.

Uhh Ohh!

man if you have seen my projects in the past i have a hard time stopping with the mods.

but im going to stay cis

what can i do with this and not go efi.

ed

You can do alot with CIS. I'm a newbie to 930s and there's a lot of knowledge on this board about modding 930s, but it seems CIS limits you to @ 400whp. To go higher than that, you need EFI. The first steps for your car I guess would be for a free flow exhaust. Then you add in a bigger intercooler and turbo. Lots of different turbos out there that guys have used: k27, k27hfs, k29... I have a k29 on my 86 and the turbo starts spooling @ 3k and pulls hard from there up to redline. I have no experience with the k27 variants. Just make sure you up the fuel as you don't want your car running lean at WOT. After that, you would be going into the motor with cams and P&Cs.

Actually, my friends CIS 930 makes 450whp at 1 bar which is a very strong CIS motor indeed.

Easy mods are headers/muffler, intercooler and K27 or K29 turbo (only go with the K29 if you are planning mods below)

Next step would be cylinder head porting, Raceware cylinder head stud kit and 964 cams.

Icing on the cake is 98mm P&Cs with 8.0 compression and Carillo/Pauter rods.

When I first went down that path, I did as you're doing...researched what others had done. I wanted the motor to come alive with at least some of the untapped potential sitting under the hood. After some time and money has passed, I ended up with:
removed the cat converter
installed a Fabspeed muffler
upgraded to a K27 turbo
modified air intake (similar to Powerflo, using K&N cone)
upgraded to a larger intercooler
added boost adjust to enable up to 1.0 bar
Aftermarket boost gauge
Swapped out the stock WG for a Tial 46mm
installed Andial's outdated enrichment system...for when I'm running at 1 bar
already had MSD ignition
Kennedy Engineered clutch PP to handle it all
Innovate LC-1 with analog gauge (soon to be installed)

There you have it. All bolt on stuff. You really can't do too much more engine-wise without getting inside of her.

hey thanks guys all good stuff

mark i think im gonna go the same path you took and go bolt on at this point.

gonna start with exhaust and go from there


thanks

nice looking car, good luck on all the mods, you're in for a real treat

IMO the first thing you should do is to lower your car...

yes you are right im gona try for a 1" drop do you know how many teeth on the torsion that is for the rear?

i know the front is very easy :D

ed

You may get away with the small amount of adjustment on the rear if you are only going to drop 1"

I am not an expert but there are couple of ways to go so identifying your goals up front can save you money.

Irregardless, the best opertunity is fixing the restriction after the turbo. Get the lowest restriction muffler you can handle. This will make for faster turbo spool, increase effecency, and deliver more HP. My favorit is a bit SS glass pack that exits on the left side.

I belive the stock heat exchangers are a solid set up and do not have the potental to crack that the after market shorties may have.

I also suspect most the of the reduction in lag attribuited to the high dollar systems is in the muffler not the short tube length.

The added power attribuited from the shortie systems I suspect is really from the ineffecent wast gate circut that tricks the WG into delivering more boost.

Next is the Turbo. This is where you should decide what your goals are.

A larger turbo like a K27HF has a biger compressor wheel and can make monster HP, will run a bit more effecent at higher rpms, and will have a softer and latter boost onset.

A K27-7200 from the factory 91-94 C2 Turbos is great turbo up to around 375HP and it but comes in with less lag and much harder boost onset. More fun in the street I would say but no bragging rights.

A better intercooler is expensive but is free HP. I also alows you to run more boost for even more HP. Just adding an intercooler can be good for 20-30hp with out adding any boost.

With the lower restriction muffler, K27-7200, a .9 bar spring and a better IC you can have a very nice running car that works will with the stock cam, ports and compression.

Note that changing cams helps the motor breath better as dose larger intake ports. However, this is not totally reqired for big HP.

The 930 has small ports to work with the CIS fuel injection. CIS squirts fuel at all time and the fuel just sits in the port untill the intake valve opens and the air starts rushing by. Porsche had to make a small port in increas the volicity of the air flow to get the air and fuel mix properly for better emmissions.

As to the cam. The 930 cam is a low rpm torque cam. Going to an SC or C2 cam can help breathing but actually lowers the effective compression ratio for a small reduction in pre boost torque. Many have make a lot of HP with small ports and stock cams.

Playing with the WUR and ignition has some potental.

The WUR from a 76/7 turbo reduced Control Pressure with a loss of manifold vac as soon as the throtle was cracked. The 78-94 WUR required .5 bar of boost before it reduces CP. The differance can be felt in throtle response as lowering the CP sooner alows the metering plate to move easyer and the car to come up on boost quicker.

Your WUR can be modified to act this way.

On the ignition side a programable ignition would be the best. Or on can to a MSD system that has the built in boost retard function and have the distribuitor modified and recurved to work with it. The side benifit to an MSD system is 930 ofter will be run a bit rich and with the low compression it is more difficult to lite the mix. The muliple spark of the MSD can help with this.

If you need to go through your motor, making it biger seems to have a double pay back with better lower end an more HP.

May have found that gears can transform a 930 as the wide gear spacing can take you out of you power band quite a bit of the time.

Good luck.

Sorry about the misspellings as my spell check did not work and I was rushing.

911st, I had to read the section about cams a few times and still didn't completely understand it.

Could you elaborate for me please?

TIA

Sorry, basically it is not worth the expense to just change out the cams.

SC & C2 cams open the intake and exhaust valves higher and longer so they do breath better.

Because they are open longer they do not fully close the intake valve on the compression stroke as soon as the stock turbo cams do. This makes for a little less effective compression. Less compression means less pre-boost torque.

There have been a lot of guys that have been able to put out monster HP with the stock cams and stock ports so it is not a must have.

My opinion is first low back pressure muffler, then turbo, then intercooler as a best practices approach. Most go out and spend a pile on a header system.

With a 930 most of us are hooked on the big HP numbers as boost is addictive. Under boost the C2 cams and the SC cams will help make more total HP. They can help preboost but to work best some measured compression should be added back in.

I would not go to the expense of just changing the cams. If I had the motor apart anyway I would go with the C2 cams and shave the head to get back some of the effective compression and would port the heads at the same time.

Porsche did a couple of things with the 930 in the name of emissions. They put in a restrictive exhaust with thermal reactors or a cat; small ports to increase velocity to aid in air-fuel mixing; they put a low lift no over lap cam to keep exhaust gasses out of the intake tract and to speed up air flow for better air-fuel mixing; and, they left the cooling fins off the top of the cylinders so the motor would heat up and run hotter and to work with the cat. (Like the 5 blade cooling fan on the 75-77 911's).

I am not an expert so please take my comments with a grain of salt.

Hey Ed,

Good place to start asking questions for sure! As a numbers person I focused on results when deciding on changes (ie...did this change and went from X to Y rwhp). The best example I can offer is a stock 91 Turbo running 1 bar vs a stock 91 Turbo running .8 bar with headers and no cat. Both cars run on the same dyno same day. Headers w/ low restriction exhaust made over 100 ft lbs more torque at 3k rpm then stock. Peak HP was the same (but .8 bar vs 1 bar). The aftermarket exhaust seems to be a great place to start....(for the money).

more power
 

i like the idea of putting more power down low in the rpm where it is lacking:D

im going to look at exhaust, who makes a good set up for the money?

i dont need to spend the most just want a good fitting setup. im not to worried about sound just seat of the pants.

thanks for your imput

ed

911st, I don't think I've ever heard of a cam being described as altering CR. It does make sense though at low rpm.
However, increasing the engines CR to compensate for a wilder cam must mean that when the engine 'comes up on the cam' the CR will be higher than it previously was. So when the engine is on boost you must need to lower the boost level too?

TIA

I've being thinking about what I said above and wonder if instead of lowering the boost level that the ignition could be retarded to compensate instead. This may mean no loss of max bhp/tq along with a quicker spool of the turbo and a more flexible engine on boost (higher revving).

There are a host of things that can be done to improve the 930 engine. All of the above listings are tried and true. Typically a slow and incremental approach is better than doing it all at once. I have been involved in far to many truely nightmarish scenarios where owners try to do it all at once and get completely screwed by the tuner or mechanic.

I do have to dissagree about the cams. SC cams alone can produce more off-boost torque in a 930 3.3L than in the 3.0L N/A SC engine they came out of. This is the first thing I noticed on my engine, and the dyno told the tale. Cam and ignition timing are HUGE contributors to improved off-boost performance. It's not just the cams but the proper tuning of the system. Just tossing cams in with the same stock settings is not optimal.

I can set you up with a light weight free-flowing muffler. Check out my website for a few options.

I suspect changing the cam dose not effect compression enough to change the need to boost. However, it is possible to run higher compression pistons and make the motor more efficient in other areas like ports exhaust (equal lenght) etc and be able to run lower boost for better pre boost power and the same net HP.

I had a 78 and 91 Turbo. I believe Jeff's example of the 91 turbo is and example of the opportunity of changing the muffler. I am suspect of changes in the headers making more HP, it is the wast gate circut design on the headers that bumps boost.

Getting the same peak HP .8 bar and 1 bar could happen as the K27-7200 comes in fast and hard but dose run out of boost around 380fwhp. I had the same thing happen.

If I had another 91T I would get the cat bypass pipe, keep the stock low restriction muffler, mod the WUR to a boost sensing, and put new 2-5 gears from a C2/4. After that I might look at a bigger turbo.

Some have reported that when they re-timed the stock cams it added to pre boost power.

I suspect a lot of people miss the opportunity on the ignition side.

Brian, what did you find to be the best cam timing settings for different cams on an internally stock 930 engine?

The best cam setting depend on the setup. If you have stock C/R and ported heads with a big turbo then you may want to dial in more torque. Bump the C/R, stock heads, smallish turbo and you point it to the big end. Driving habbits play into it as well. Lots of variables.

quite zork
 

checked out your site im gone be ordering the quite stock exit muffler. but first i need to get the carrera back up and going then onto the turbo upgrades.

ed:D

You won't be dissapointed. Just let me know when you are ready.

1.0 bar then back to .8
 

while out driving tonight i noticed that when running a hard pull in third gear my boost gauge would max out at 1.0 bar then drop back to .8 around 6k rpm. is this normal :confused:

man what a great car to drive. i have really enjoyed this thread im really learning alot.

how many cars put a smile on your face just thinking about them


ed

Hey Am I Lucky Or What At 1:18 Alaska Time Im The Only Person Online? Is This An East Coast Forum Hmmmmmm??

I Feel All Alone Here

I'm here.

Not really, that's quite a variation of boost.

1 of 3 possible things are happening.

1. Your turbo is too small and can't make enough boost to maintain 1bar all the way to the red line.

2. Your wastegate cannot dump enough exhaust gas so the turbo overboosts. This could be bad header design, sticky wastegate or simply the wastegate dump pipe being an obstruction.

3. Possibly your recirculation valve/assembly is wasting boost so you cannot maintain 1bar all the way to the red line.

hey nathan thanks for the info and i should have gotten back to you it ended up being a sticky wast gate but all is better and im working on three other p-cars and mine is just sitting idle.

can anyone tell me what kind of up grade in performance a set of s/c heat exchangers and one of RarlyL8's quite muffler would yield. im not going to have the funds to go headers at this point as im trying to juggle money between three cars. would like to see 300 H.P. i have the 3.0 heat exchangers from a 78s/c here in my garage is the main reason i would like to run them.


thanks guys this forum has been great.

thanks ed

What heat exchangers do you have currently?

A free flowing muffler is good for ~12HP when compared to a stock Euro muffler on a 300HP engine.
That doesn't sound like much but as others can attest, it is only the beginning. The engine is uncorked. It revs quicker, spools faster and makes noises that will have you laughing like a little girl. It simply transforms the experience.

You want 300HP? That is easy. Stock Euro heat exchangers, K27 turbo, intercooler upgrade, stock boost and a free flowing muffler will pop you over 300HP at the rear wheels.

Want to loose over 1000rpm of turbo lag over the 3LDZ? Bolt on a K27S.

Here is a picture of a Euro exhaust. You will note the similarity of the heat exchangers to those of the Carrera and SC. They are the same.

http://forums.pelicanparts.com/uploa...1231472381.jpg

i currently have thermo reactors that the PO out on the car to make it emission compliance. im wanting to put on the sc heat exchangers i have one of your left side exit quite mufflers. and the k27 intercooler up grade then start playing with suspension.

thanks for the pic that looks like what i have.

im looking forward to a little noiser car. :D but not to noisey
http://forums.pelicanparts.com/suppo...ys/politie.gif
http://forums.pelicanparts.com/suppo...ys/politie.gif

thanks ed

Brian sell him a Zork!

Yes the fun tube is a circus on wheels, but it IS noisy! Ha!

The regular Rarly8 exhaust/muffler with the small can is a good option. Good quality and excellent sound - just right!

it will get a rarlyl8 small can for sure as i found some youtube sites with a sound clip and it is a thing of beauty:D

thanks guys for all the help.

now for the next question with our ambiant temps never over 75 deg. with a rare 80 deg. can i get away with the stock intercooler and the k27 with the s/c exchangers and the rarlyl8 small can?

cheers ed

Yes, as long as you run stock boost.
Turbos LOVE the cold air. The whole deal is keeping inlet temps down. Heat cost power and leads to detonation. I actually have to block off part of my tail in the "winter" to keep the engine operating temps where they need to be. Summer is a whole different ballgame ...
Shoot me an e-mail and we can talk K27 if you like.

thanks for the reply brian,

ill be getting in touch with you before this winter up here is over, on turbo and muffler.

how about air filters or intake is there any reason to get away from stock?

besides it looks like it would free up some space.

thanks ed