Yet another 930 rebuild begun

[hobieboy]

Mike, I'm doing a very similar rebuild as yours but with a K27HF; so would be very interested in your progress; particularly the map for the MS ECU

DonE, any idea how does the Bosch 52lb injectors compared with the Siemens 55lb ones? Quality, injection pattern, etc.?

One question I have is: how would one estimate hp? Say with Mike's build, would one expect 400rwhp? 450rwhp? or more?

thanks...

[mppickett]

Hobieboy,
I don't have a map for the MS yet but if I get there first I'll be glad to share. Regarding injectors, I understood that the '96-'98 turbos used 38# injectors and made 408 hp at the crank (someone check me on this if you have better info). I'm betting I'll end up with just a shade under 400 rwhp at .8 bar based on what others have made. That would be plenty for what I plan to use the car for.
Mike

[snowman]

I would recheck your injector sizes. At 50lb of fuel pressue you need like 58# injectors. See following links for calculators
http://www.iroczone.com/calcs/injectorsize.htm

http://www.rceng.com/technical.htm

I have 42# injectors in my BMW M635 and it only makes 300 HP, thats injector limited. fuel pressure is 48#.

[DonE]

Originally posted by hobieboy
Mike, I'm doing a very similar rebuild as yours but with a K27HF; so would be very interested in your progress; particularly the map for the MS ECU

DonE, any idea how does the Bosch 52lb injectors compared with the Siemens 55lb ones? Quality, injection pattern, etc.?

One question I have is: how would one estimate hp? Say with Mike's build, would one expect 400rwhp? 450rwhp? or more?

thanks...

I would recommend you speak to an expert about your injector question - someone like Marren Fuel Injectors for example (www.injector.com). I have 72lb Siemens injectors which are sloppy at low rpm, but 72lb is a big injector for a 500rwhp motor.

As for estimating Mike's hp, I would estimate a low of 365 and a high of 390 rwhp. Why? Small injectors, .8 bar boost, K27 (small turbo), 964 cams. It's my opinion (please, no offense Mike) the engine is a bit mis-matched, even for a mild turbo car.

[mppickett]

None taken whatsoever. I'll look into upsizing the injectors. DonE, Snowman - I appreciate the links to the calculators! By the way, does anyone have a part recommendation for replacing the throttle position switch on the Carerra 3.2 intake with a full potentiometer TPS (for the Megasquirt EFI)?

Thanks,
Mike

[hobieboy]

Mike, would really appreciate if you can share your map later on I've just disassmebled my engine and the rebuild part will start probably in another week or 2.

BTW - why do you need a TPS? With MS, I'm planning on using only MAP and RPM for fuel calculation?

I also agree with DonE - you should consider a better turbo like the K27HF.

DonE - thanks for the suggestion. Will give them a call. I sent an email to RC Engineering but nobody replies to my inquiry

[beepbeep]

Originally posted by hobieboy
BTW - why do you need a TPS? With MS, I'm planning on using only MAP and RPM for fuel calculation?

Accelleration enrichment.

[gtu935]

All nice stuff in this post. We have a 3.3 liter turbo engine. Pinned case etc. Stock flat top Mahle pistons and stock cylinders. Although we run 72 lb per hour injectors., a k-36 turbo, sc cams (because we had them) a large custom intercooler and haltech fuel management. The heads and cylinders have Nirist rings. This motor turns HP from 480-680 depending on boost. For three years the engine has held together with no problems.

Go with at least 52 Lb injectors

Good luck with your project. Dyno Tune for sure

[gtu935]

When we build an engine for race or street we ask the customer his/her HP wants. Then we go from there with injectors choosen for the wanted HP range. Injectors are rated and prefer to work at fuel pressures from 38-44 lbs. At that fuel pressure the spray pattern is optimized. A rising rate fuel pressure regulator will work if you need to run small injectors for good idle charactoristics but, I prefer to run the correctly sized injectors for the wanted horsepower.

[DonE]

Originally posted by gtu935
All nice stuff in this post. We have a 3.3 liter turbo engine. Pinned case etc. Stock flat top Mahle pistons and stock cylinders. Although we run 72 lb per hour injectors., a k-36 turbo, sc cams (because we had them) a large custom intercooler and haltech fuel management. The heads and cylinders have Nirist rings. This motor turns HP from 480-680 depending on boost. For three years the engine has held together with no problems.

Go with at least 52 Lb injectors

Good luck with your project. Dyno Tune for sure

I appreciate when tuners post their findings and recommendations. Thank you.

On a personal side, I like to see that you have a fairly big HP motor using SC cams (480 on the "low" side). Further proof you don't need big cams to make good HP on a turbo motor.

[gtu935]

I have a 930/935 type car I run in Porsche Club racing. The engine in this one is a 3.8 single turbo. The crank has been modified and has 2" rod journals with NASCAR type bearings in order to turn higher RPMs (8600). I had cams ground special for this one, similar to 962 cams, for the higher RPM capability. The intake system is individual throttle bodies with two 55 lb per hour injectors per cylinder. also controlled with Haltech this engine produces 800+
I found that the higher RPM was really not needed to make the power but, it is nice when accelerating out of turns on the track..

[hobieboy]

Originally posted by beepbeep
Accelleration enrichment.

Goran, going from memory (still need to read MS manual in more details), I think you can use rate of change of MAP for accel enrichment so can do without TPS?

[beepbeep]

Originally posted by hobieboy
Goran, going from memory (still need to read MS manual in more details), I think you can use rate of change of MAP for accel enrichment so can do without TPS?

Yeah, It could probably work depending on how big plenum you have but advantage of using TPS is that it's pre-emptive.

I don't know how big difference it makes though. Probably not much on inherently laggy turbocharged engine.

[hobieboy]

Originally posted by beepbeep
Yeah, It could probably work depending on how big plenum you have but advantage of using TPS is that it's pre-emptive.

I don't know how big difference it makes though. Probably not much on inherently laggy turbocharged engine.

My concern with using TPS is that when going from cruise (no boost), it doesnt make sense to enrich just yet unless boost is up. I'm hoping the "standard" map will take care of rising fuel need in this case (as RPM will rise) until boost comes in.

[DonE]

Originally posted by hobieboy
My concern with using TPS is that when going from cruise (no boost), it doesnt make sense to enrich just yet unless boost is up. I'm hoping the "standard" map will take care of rising fuel need in this case (as RPM will rise) until boost comes in.

I understand what you are saying, but I don't agree - at least not with the TEC3r. By using the TPS, I can set the software to add fuel via a variable time pulse width adjustment that adds just enough fuel (say, and extra .5ms over 1 second) that immediately reacts to TPS movement and gets the engine to respond quicker to WOT or really, any acceleration. With a CR of 8.0:1, this is a big difference when compared to a NA motor at 10.0:1 on the track. This feature will help spool the turbo just a bit faster.

I am a firm believer in using the TPS and MAP (not the "blend" feature) to tune a turbo motor. The quicker you can get an AFR to 11.5:1, the quicker the turbo will act in bringing up boost. A combination of TPS and MAP will give you immediate fuel (and spark advance, if you tuned it correctly) and is a noticable kick over not using the feature.

[hobieboy]

umm... one more thing to resolve then
Don, did you use the stock TPS or ???

[DonE]

Either will work. I use a ford part because I have an accufab TB.

[mppickett]

So after 20 hours this weekend of swabbing out nooks and crannies with an alcohol soaked Q-tip, cleaning old gasket material off of critical surfaces, checking oil passages, punchlisting gaskets and seals and clean, clean, cleaning the ever loving snot out of everything with brake cleaner, link-free wipes and alcohol.... I've got a table full of parts bagged and tagged and ready for assembly. I'm meeting Chuck Miller at MillerSports tomorrow morning so he can oversee me beginning to put the beast together. I'm so tired... but excited. Pictures as entropy retreats.
Mike

[mppickett]

Some pics for your viewing pleasure. Points of interest include the shuffle pinned case and the steel intermediate shaft gear and matching gear on the crank. The steel intermediate shaft and crank gear are from a 964 engine. They measured out perfectly with the same gear ratio. Should be quieter and more durable. The rest seemed to go fairly normally. Progress! Now I'm starting to gather my thoughts about the Megasquirting of the beast (any working config files will be gratefully accepted

Mike

[sand_man]

LOOKING GOOD! I should have my parts back from Performance Developments in a week or so...then I'll be right there with ya!