Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Outlaw 911
 
Join Date: Apr 2008
Location: Northern Colorado
Posts: 66
Opinions wanted....

Hi Boosted Pelicaners –

Here is the situation- about 3 weeks ago I bought a 77 vintage 930 3.0L Turbo motor complete. Pretty darn original. The exceptions are the eliminated thermal reactors and the missing air pump.

The motor was disassembled when purchased and after a few hours of inventory – it appears to be all there from the fly wheel to the muffler, including electrical harness, injection, engine tin, AC compressor. The only exceptions are the driver’s side chain tensioner oil line and some of the cylinder cooling air guides.

The Good –

77K mile engine – appears to have had a top-end rebuild recently.
WebCams – stock grind? Has the number 150 under the Webcams stamp.
No broken rings or damaged pistons.
Crank and rod bearings in good shape.
Updated to Carerra tensioners.
Heads rebuilt with new guides.
Heads professionally ported to 36-38mm size – very well done.
Rockers appeared to rebushed.

The Bad –

2 broken head studs.
2 of the cam lobs on the same cylinder are rough. Looks like someone ran it with valves misadjusted - way too tight?
2 of the rocker arm shafts were stuck in their bores – and it took a little work to get them out their bores – and those bores were slightly scored – is this OK?
And in general the it is an oily, stinky mess.

I am planning on rebuilding this engine in the coming year and do the following:

Install late model Carerra intake.
Swap over to electronic engine management.
Run crank fired distributorless ignition.
Install an intercooler.
Upgrade the cams (SC or 964)
Use a modern turbo header/exhaust.
Use a modern turbo (a K27 version).
Gut the stock muffler and run duals out of it.
Use a modern blow off valve or recirculation valve.
Use a modern waste gate.
Run either a short G50 or re-geared 930 transaxle.

The goal is a 350hp to 400 hp engine that is happy on the street, but can handle track duty, with a useful power band from 2500 to 6500. I am NOT interested in a dyno queen with big numbers - this 911 will be used for DEs, autox, fun rallies and OLOA.

I need some help deciding a few items:

1 What sort of compression ratio should I aim for? Currently, it is at 6.5 to 1. I will not run more than 14 psi of boost and would like a peppy off boost engine.
2 What is the cost effective way to increase the CR? I have heard of folks machining the heads to allow the cylinders to fit in deeper (1.0mm) to get a CR bump. Is this a good way to do this?
3 What cam shaft grind should I run? Since this is a 3.0L – is the 964 cam with ported heads too much?
4 Suggestions on the K27 turbo are welcome. It is still running the 3LDZ. Should I have this turbo upgraded with a more modern compressor side or just pitch it and start over?
5 This engine has 901 part numbers for the cam boxes – yet my 83 3.0L SC motor has 930 part numbers. Is something a miss here?

Any other input would be more than welcome.

Thanks

Outlaw 911.
Old 10-22-2009, 04:02 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Turboo934's Avatar
 
Join Date: Jul 2007
Location: Taoos New Mexico
Posts: 668
76-77 cam boxes have a 901# but are 4 bearing boxes, like the RSRs. 3.0 turbo motors are great , put an inter-cooler on it & 2nd front oil cooler, your good to go.
Old 10-22-2009, 04:23 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
lite75's Avatar
 
Join Date: Jan 2007
Location: Bellingham WA
Posts: 842
Garage
8:1 compression using pistons, 964 cams, new turbo (many better options) headers with short primaries and intercooler. The G50 will make a bigger improvement over the EFI if the CIS is set up correctly.
__________________
75 930, 76 930, 83 SC EFI turbo
Old 10-22-2009, 05:45 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Garrison's Avatar
 
Join Date: Apr 2006
Location: Denver
Posts: 729
Garage
If you are going to get your 930 box re-geared I would suggest GBOX in Boulder...great guys to deal with.

I am running a K27S on my 930 and love it compared to the stock turbo. Many variants for sure on the turbo and I am sure some of the turbo experts will chime in here...

For sure get an intercooler for it. There is someone that has posted a Garretson specific to the earlier 930's with the 3L over in the classifieds... maybe check that out. Intercoolers for SALE!!

Headers will help with off boost power, and once again many types to choose from. As for a muffler the less back pressure the better. Rarly8 on here makes some great mufflers and headers...

Welcome to the club and surprised no one has said anything.... but we want pictures!!!
__________________
1996 Porsche 911
2013 BMW 335xi - Wifes car
2007 4Runner - 4x4 for Colorado snow
Past: 1988 Venetian Blue 911 Targa, 1983 Black 930, 1984 Black 911 Coupe
Old 10-22-2009, 06:59 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Not an expert but here is my two cents.

K27-7200 comes in very fast and hard and will work well up to 400hp on an efi 3.0 motor and could be a good fit. A K27-7006 has a larger hot side for less back pressure and more HP on the track. Do not know if there are any more new ones out there for sale. They come on boost a about 300rpm later I suspect but with EFI and some compression that may not be an issue. The GT-35 might be worth looking at.

Pre boost response is a combination of tune, motor size and compression. 8/1 makes for good low end response.

However, unless you have a very efficient turbo/inter-cooler, run race fuel, have fire rings cut into your heads and cylinders running 1 bar might be close to being over the edge.

JE turbo pistons are your best way to get compression. However, with you stock compression you could go to 1.1 bar.

With a 3.0 you can run a higher rpm safely and might consider a cam that will support 7k rpm. With the right build (programmable boost level by rpm) you could have a very wide flat power band.

As an option you could have your cylinders bored out and re-plated bumping you to a 3.2.

If you are truly going to go the way you say, it might actually be better to sell the 3.0T and start with a stock 3.2 Carrera motor as it already has great turbo cams, is a larger motor, has a great intake manifold already fit to the heads. Also, it has a very usable distributor that with EFI and MSD could make for a solid ignition for a bunch less tha distributor less system, .
Old 10-22-2009, 08:23 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Outlaw 911
 
Join Date: Apr 2008
Location: Northern Colorado
Posts: 66
Thanks for the input guys...

Per 911ST - 14 psi would be a over the top - I am going to dial it down to 11psi - I want a good thermal and knock safety margin.

Turbo - looks like the K27- 7006 is a good choice. I like the idea of less back pressure and a bit more thermal safety margin. It will also deliver power up top.

I am going to run a H2O intercooler system - because I want to run a ducktail and the gen 1 turbo tail. I know this is a more complicated setup than A/A, but there are a number of additional reasons I want to go this direction.

I am still struggling with cam choice - the SC cams according to the group, will work great, but am limiting the power band to 6K? My gut is telling me NO. Underboost, the less agressive cams - (compared to 964) is not an issue in the upper RPM range (5K to 6.5K) - but I am a Turbo Cave Man (TCM) - or Boosted Knuckle Dragger (BKD).

It seems that a fresh 930 3.0L with SC cams, opened up ports/Carerra intake, dedicated turbo header setup (short primaries), a CR bump, electronic engine management, and a more modern turbo (not too big)/intercooler setup - it would have crisp off boost performance w/sparkling boosted performance. Put this setup in a 2400 lbs chassis with a G50 or built 915...should be fun.

On the subject of 915 boxes, I have read a lot of stuff on durability, but it seems like qty 3 915s can be built for the cost of one G50? Will a 915 hold up on the track? No smokey burn outs, no drag starts - just track work - am I foolling myself?

Outlaw 911
Old 10-23-2009, 08:56 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
lite75's Avatar
 
Join Date: Jan 2007
Location: Bellingham WA
Posts: 842
Garage
Drive a g50 car and your mind will be made up, biggest improvement I've made to date. With a quick spooling 3.0 you'll be ripping through those gears like a madman, no mercy required!
__________________
75 930, 76 930, 83 SC EFI turbo

Last edited by lite75; 10-23-2009 at 09:23 AM..
Old 10-23-2009, 09:18 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Note on the turbos. If you stay with 3.0 you are 10% smaller. A 7200 on a well set up CIS is going to get full boost by close to 3100rpm. This would put you at about 3400 if you were CIS but probably sooner with the EFI effect. A 7006 on a well set up 3.3 CIS will see full boost by about 3300-3600 so figure about 3500 with EFI. I belive that on a race motor you want full boost about 3500 to 3800 to minimize back pressure. This might be good for another 30HP.

Both will have fast spool times. (Boost threshold, spool time, full boost time, all are different. Spool time is the 600 rpm or so it takes the turbo to go from boost threshold to full boost.)

You might want to talk to "Cam Grinder". There are more modern cams out there. However, you can time an SC/Carrera cam to make HP to 7K I believe. Just copy the 1977 euro 3.0 spec. Most set there SC cams for low end to make up for the CIS's lack of responsiveness.

Not an expert, just what I believe so far.

Check out Bell Inter-coolers (BIC) for a water to air IC.
Old 10-23-2009, 09:54 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,563
Garage
7006 is good for top end. Laggy on the street. K27S is good for bottom & midrange, 7200 good for midrange, HF good for midrange and top end.
Cams need to follow the turbo. For good midrange use an SC or like. For top end use a 964 or like.
The 915 will not stand up to track use much past 300 ft/lb torque. Too much heat. You can outfit with spraybars, cooler and WEVO but may spend more than it's worth. 930/4spd with low R&P is a good option for medium power cars.
__________________
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 10-23-2009, 11:09 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
lite75's Avatar
 
Join Date: Jan 2007
Location: Bellingham WA
Posts: 842
Garage
The G5001 has lower, closer gear ratios than the 4 speed, or as Rarly knows the 915 ratios work well also. Makes a huge difference on 3.0 if your turning it up tight. Use good valve springs and light weight retainers.
__________________
75 930, 76 930, 83 SC EFI turbo
Old 10-23-2009, 11:28 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
3 restos WIP = psycho
 
kenikh's Avatar
 
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,729
FWIW, running a water/alcohol injection system will allow over 9:1 CR and over 1 bar of boost with twin plugs for some REAL off the line dividends.Check the methanol injection thread on this forum for the turbo 3.2SS that runs 9.5:1 at over 1 bar on 964 cams w/ efi.
__________________

- 1965 911
- 1969 911S
- 1980 911SC Targa
- 1979 930
Old 10-23-2009, 12:47 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Wo ist die Rennstrecke?
 
DonE's Avatar
 
Join Date: Mar 2004
Location: Brooks, GA
Posts: 1,211
Quote:
Originally Posted by Outlaw 911 View Post
Thanks for the input guys...

Per 911ST - 14 psi would be a over the top - I am going to dial it down to 11psi - I want a good thermal and knock safety margin.

Turbo - looks like the K27- 7006 is a good choice. I like the idea of less back pressure and a bit more thermal safety margin. It will also deliver power up top.

Quote:

If you're going to do EFI as you indicate below, don't even screw with the K series turbos. Call some of the Garrett distributors and explain what you are doing (ATP and TIAL have techs who know older Porsches) and see what they recommend. Even with your lower displacement, the 7200 will run out of breath over 5800 rpm and feel like hitting a wall. The 7600 is not anywhere as efficient as the Garretts and the Garretts have dozens of combinations - go for a turbo designed in this century.
I am going to run a H2O intercooler system - because I want to run a ducktail and the gen 1 turbo tail. I know this is a more complicated setup than A/A, but there are a number of additional reasons I want to go this direction.

Quote:

Very cool - consider Kenikh's comments. I wouldn't push the CR to 9:1, but with 3.0L you're gonna need something to come out of the hole (nothing substitutes for displacement).
I am still struggling with cam choice - the SC cams according to the group, will work great, but am limiting the power band to 6K? My gut is telling me NO. Underboost, the less agressive cams - (compared to 964) is not an issue in the upper RPM range (5K to 6.5K) - but I am a Turbo Cave Man (TCM) - or Boosted Knuckle Dragger (BKD).

Quote:

I am not a 3.0L expert. But if I were doing this and it were for the track, I would lean towards a set of GTII cams. There is a builder in Memphis who took a 2.0L motor and built a screamer using GTII cams (Pat something....).
It seems that a fresh 930 3.0L with SC cams, opened up ports/Carerra intake, dedicated turbo header setup (short primaries), a CR bump, electronic engine management, and a more modern turbo (not too big)/intercooler setup - it would have crisp off boost performance w/sparkling boosted performance. Put this setup in a 2400 lbs chassis with a G50 or built 915...should be fun.

Quote:

Should be fun. Why did you choose a 3.0L? If I had it to do again, it would be a 3.6L TT built for 9000 rpm in a 2400lb street car. But that's me....


On the subject of 915 boxes, I have read a lot of stuff on durability, but it seems like qty 3 915s can be built for the cost of one G50? Will a 915 hold up on the track? No smokey burn outs, no drag starts - just track work - am I foolling myself?

Quote:

Have you ever driven a 915? It would be great to have a low cost 5sp solution for our cars, but low cost and solution are not synonymous when building exotic Porsche motors. For track, the only solution is the G50 ($ = ouch).
Outlaw 911
Please keep us informed - sounds like you're gonna have a lot of fun.

Last edited by DonE; 10-23-2009 at 05:14 PM..
Old 10-23-2009, 05:10 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Forced Induction Junkie
 
WERK I's Avatar
 
Join Date: Jan 2003
Location: Wisconsin
Posts: 3,291
Garage
Outlaw911,
Thanks for sharing your project dreams and goals with us. A short-stroke 3 liter screamer sounds like a great idea.

I'm with Don on the Garrett turbo selection. They are more modern than the KKK's and they give you greater latitude in finding the perfect fit. Find a highly recommended turbo vendor and state your goals. One other thing that people fail to realize with the Garrett turbo's is the compressor outlet temps. With a properly matched turbo, you will realize lower outlet temps, more than likely, than with an off-the-shelf turbo. This means the IC will have a greater margin of safety and lower IC outlet temps.

Regarding the transmission, you can get by with a 4 speed if you design the the gear spacing/ratios for the track(s) you're running on. Put the first gear ratio for the slowest corner and build out from there. You are probably going to have a pretty tall first gear, but a friend of mine is running a 930 at Road America and built his first gear for Turn 5 (a very slow 90* left hander) and spaced his ratios out from there. He found he didn't really need a 5 speed for this track.

In respect to your cam selection, match the turbo to the cams. Talk to your turbo vendor or cam vendor and express your targets. Having them grind a cam to your specific needs is really no more expensive than picking an off the shelf cam. Even then, I seriously doubt you'll be running more than 7K RPM at the top. Running 8K RPM takes some serious money to give this generation of engine serious longevity.
__________________
Dave
'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P

Last edited by WERK I; 10-24-2009 at 08:00 AM..
Old 10-24-2009, 07:54 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Registered User
 
copbait73's Avatar
 
Join Date: Nov 2003
Location: Chesterfield IN
Posts: 1,316
Garage
I'm reading this thread and I'm still not sure your intentions on charge air cooling.

I read you are looking at a liquid loop charge air cooler system. Driven by the same desire to retain my IROC deck lid I did the same on a twin turbo 3.0L set-up.

I think all basic systems air to air, air to water (liquid loop) and water/alcohol air stream injection have their benefits and drawbacks. It’s a decision driven by application compromises. Liquid loop will fit the technical requirement and retain the stock tail however you should consider this type of system will probably be heavier plus the weight is where you least desire it for a track car.

The air to air CAC is ideal for the 930 Porsche because:
You already have a serious fan to draw the air
You need a tray type spoiler anyway
You need to use the lightest installed system available.

My vote is to hang the non-CAC tail on the wall and convert to air to air charge cooling.

If you feel the need to supplement this air to air CAC with a water/alcohol injection system you can do that at a later date however one that has noticeable benefit is capable of consuming meaningful volumes of fluid when applied to tracking use.

My belief is once this community gets a handle on what is truly happening with head temperatures in a track type environment they will find supplemental water injection has its benefits if for no other reason than insurance. I say this also based on the direction most everyone takes in raising fixed compression ratio.

I say lose weight, get gears, keep C:R low and boost like hell. But then I’m an old school turbo guy.
Old 10-24-2009, 09:27 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Your stated goal is to fit a Duck Tail, build a flexable 3.0 Turbo that is not over stressed and that makes near 400hp.

Here is an idea.

Keep the 930 pancake manifold and convert it to EFI.

This would allow you to build a custom air to air inter-cooler that will fit under your ducky!

(I have wanted to do this.)

The pancake manifold if ported at the heads will easily support 400 EFI HP.

Under boost as long as the ports are equaly sized to fit the head it will flow reasionable balanced air.

Side benifit is it has less volume that has to be presserized when comming up on boost.

Open the intake ports up to about 36-38mm. Custom cams -- version of hi lift GrupeB-or- SC/3.2 cams timed for higher rpm. I am guessing that a 3.0T is not going to need C2 cams as it takes smaller gulps of air. Further they are not designed for use at higher rpms with there steep ramps and higher lift. If my car I would build it for safely run to a 7300rpm red-line but with good power from 5k-7k.

Set the compression at 8/1 for responsive low end and faster spool withboost at .8 bar. Or stay with 7/1 and go for 1 bar boost for about 35 more hp. On race fuel you could even go past this.

Use the K27-7200 as it will support up to about 380hp on CIS or 425 on EFI which is your sweet spot and it will have very good response with the smaller 3.0 size. Otherwise, look at the more modern designs that are not based on the K series.

I suspect keeping the dist and going with an MSD single plug set up will give you a better spark than most crank fire systems. With EFI alowing for beter control over your AFR's, the smaller cylinder diameter, and open chamber/low crown piston I do not think twin plugs are going to be needed (993TT & RUF Yellow bird were single plug.) Especially if you go with 8/1 compression ratio.

This should come in very close to your 400hp target.

One potential issue with air/water IC is if there should ever be a leak in the core you can be subject to hydro lock. Further it is complicated and with the pump, radiator and plumbing will be compacted and maybe even add more weight.

What a fun project!
Old 10-24-2009, 03:19 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered User
 
Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
FYI, K27-7200 map:



GT-35:


Last edited by 911st; 10-25-2009 at 07:56 PM..
Old 10-25-2009, 07:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Outlaw 911
 
Join Date: Apr 2008
Location: Northern Colorado
Posts: 66
Wow - great input and thank you all.

So things are now starting to take shape as far as the build is concerned. Here is what I have gathered so far. 400-425 is a reasonable goal, a 5 speed is key (G50 the only option, I am not going to break my rebuilt GBOX 915).

The reason I am starting out with a 3L versus a 3.3L or 3.6L - the engine was local, very complete and at super reasonable price. If I find a good 3.2 or 3.6 crank & rods - I might consider buidling a stroker, but that starts to get into a whole different set of challenges - like robbing 7-11s and selling my organs on eBay.

1 Modern turbo - possible Garrett. I need to start my homework on this one.
2 Tunable engine management - using the Carerra intake (already have one).
3 EDS - dual plug setup- maybe- since the heads will need work - might as well put in 2nd plug. Use a cranked fired setup.
4 Bump in compression - maybe - if I find the piston/cylinder out of spec - use new pistons - otherwise I might stay with what I have, shave the heads to get a a .5 bump in CR and run slight higher boost?
5 Cam selection - something beyond SC or 964 - allowing a power band into 6500-7300 rpm range - spec turbo to match. I need to start my homework on this one.
6 I am using a H2O based intercooler for a few reasons - I have seen A/A setups that have been placed under a standard deck lid, so that might work.
7 Use a short tube turbo manifold setup - that I all ready have.

Again - I don't want to get into peak HP numbers - rather a engine that can live for 10 or 15 laps when driven at a DE that will stay in a safe thermal range, go fast and makes super cool noise.

Check out my current project - which is in front of this one...but I am making good progress.

TurboChargingDynamics.com • View topic - TCD e28 s52

and

MyE28.com: BMW E28 5-series Resource - View topic - Update 8/23/09 Project e28s52t (Adjustable Rear Subframe)

Again - thanks for the input....more is always welcome.

Here is kinda what the finished result will be - a narrow body with French rally flares - I love the look.



Outlaw 911
Old 10-25-2009, 07:51 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Registered User
 
carreraseacat's Avatar
 
Join Date: Sep 2005
Location: Singapore
Posts: 140
i have installed a 7200HF on my 3.0 lump with EFi, SC cams and 3.2 barrels and pistons.

i have only just got it running so we are in the early stages of tuning and my injectors run out of puff somewhere around 4,500 rpm! but up until that it drives very well and is responsive off boost, certainly no worse than my previous stock 3.2 Carrera did.

at 4 and a bit thousand rpm it is making about 260bhp and 225ft/lb so the stage is set!

once i source some suitable bigger injectors i will let you know how it goes.
__________________
Cheers Mark
1989 944 S2 Cab // 1983 SC Cab //1977 930 3.0 - back from the dead! custom turbokraft IC, Motec M600, 550cc injectors, individual coil packs, 964 cams, UMW HFS7200 turbo, billy boat headers, turbo thomas back box, 996T oil pump, 3.2 JE pistons and barrels = 375.6bhp // 1973 BMW 3.0 CSL // 1973 E Type FHC
Old 10-25-2009, 07:58 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #18 (permalink)
Wo ist die Rennstrecke?
 
DonE's Avatar
 
Join Date: Mar 2004
Location: Brooks, GA
Posts: 1,211
Quote:
Originally Posted by Outlaw 911 View Post
[snip]
4 Bump in compression - maybe - if I find the piston/cylinder out of spec - use new pistons - otherwise I might stay with what I have, shave the heads to get a a .5 bump in CR and run slight higher boost?
[snip]
Outlaw 911
I bought my 930 from a guy who shaved the heads to bump the compression .5. He did not (nor did I) take into consideration that the heads (and consequently the cams) are now closer to the crankshaft which put a fair amount of slack into the cam chains. After initial chain stretch (from being new), the stock cam chain tensioners were topped out and could not remove any more slack. I had to buy oversized idler pulleys from Jerry Woods to take out the slack. I could not increase cylinder shims because the deck height was correct with the shims I used (DON'T screw with deck height).

If you're willing to do this upfront, OK. Otherwise go with custom pistons and be done with it.
Old 10-26-2009, 06:40 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #19 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 05:03 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.