2.5 shor stroke engine, my plans Options

[michel richard]

So here's what I'm doing for the engine as part of my "GT style" conversion. First and foremost, I figure that an engine in a GT style car has to be rev-happy.

So, here's what I'm putting together, with the help of my trusty wrench, Ron Green of Campbell Gararge in Montreal:

Short stoke 2.5 Porsche engine:

1) Used 7R engine case, align bored, Timeserted, shuffle pinned
2) 90 mm JE pistons, 10.5 compression ratio
3) 90 mm replated Nickasil cylinders, sourced from EBS
4) Standard piston ring set
5) 66 mm counterweighted crankshaft
6) GE 80 camshafts
7) EBS racing valve springs
8) EBS valve spring retainer set for above
9) 2.0 connecting rods
10) ARP rod bolts and nuts for above
11) twin plugged heads
12) Electromotive HPV twin ignition
13) Turbo lower valve covers
14) front mounted ol cooler with "GT Style" installation
15) new bearings and gaskets all around
16) miscelaneous engine parts, stock.

I still need to figure out what to do with the port sizes in the head. The target is to have a 8,000 rpm redline, and 250 hp, although the redline is more important than the hp to me.

So that's the plan. I pulled the trigger on the hard parts above today. ( I already have the crank and the miscelaneous parts).

Induction is going to be 40 mm PMO carbs, jetting to be determined.

I'll post to this thread as progress is mad on the engine.

Michel Richard

[Brett W]

QUOTE

Very few cars run sequential injection, very little is gained by this. You forgot it’s also batch fired…again very little to be gained.

Every single production car in existence since the mid 90s uses sequential injection, Why because it is the right way to do it. Plus it is cleaner as far as emissions go. When you are tuning a car in location that demands vehicle inspections you have to be able to run it clean. Yes you can do it with batch fired, sometimes.

QUOTE

This is the one I hear all the time....who cares besides techno geeks. Sure it might come in handy on a high-end racecar, BUT a streetcar??? Come on. Just run the damn engine!

I care. I will not risk a 10K-30K$ motor with an EFI system that I can't control every aspect of its operation. Why do you think the factories work so hard on fine tuning the systems in production cars? Because they can't have the liabilty of a car failing an emmisions test, crapping out on the freeway in the middle of rush hour, or puking an engine. I want the same quality of drivability for a customers car as they would have from the factory. That means fine control of fuel and ignition parameters, air temp and water temp corrects, O2 reference, etc. Yes Simple can do some of this.

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That’s a broad paintbrush with no substance...please explain the things it ghettos its way through.

For example, it does not offer different maps for a variable cam timing engine. It does a simple switch with no way to control the parameters of the switch or what happens beyond the switch point. Same goes for the Variable intake setup on the Acura engine, the Porsche engines, or BMW engines. You couldn't control the variable intake setup on an SHO engine or traction control system on a Lexus engine. They assume you will just richen up the Fuel tables for anything beyond where that switch is activated. With one of teh systems I am working with you can control the parameters looked at before the switch comes on and the tables referenced by the ECU after the switchover. I can reference MPH, Engine Temp and TPS to alter these points.

QUOTE

In about 10min with no dyno....I counter-point that how can the average person tune with all this clutter (and dyno time). The average person is so over whelmed with information overload that they shy away from PEFI systems. Look at Michel here on this thread, I've told him that the SDS will start right up, within minutes I'll have the A/F dialled in (not that I'll have to tweak it much from the pre-loaded base line), BUT still he wants to break it in with carbs.

The average person doesn't have the understanding of FI operation to tune an engine anyways. Put the average joe on the engine dyno and then the experienced tuner on dyno and see who comes out better. Then send the two out to tune part throttle and watch who comes back with a smooth driving car. Won't be the average Joe.

QUOTE

Again the systems you use are not user friendly. Fast scrolling did take a day or so to learn all the tricks, but once you get the hang of it it's very easy. In a race app I could make a major engine change and be dialled in good enough by about the 3rd corner. Can you say that?

They are user friendly. Most users have no problems using the system. It is not for the average joe, they shouldn't be tuning an engine anyways. Good enough will get you a mid pack finish. I prefer to show up at the track with a fully dyno tuned engine and make a few subtle changes as the weather and track conditions require.

Carbs are fine, they have worked for many years succesfully. They are easy to install and relatively easy to tune. For Michael's situation he will sacrifice some drivabilty for power up high because of the carbs. I don't relish the days of clogged idle jets and having to change my jetting with season changes.

QUOTE

I'm sorry but this is the biggest laugh! How do you save them Money! With dyno time? With a system they don't have a clue how to tune? Please, it makes you money every time they have an issue because they can't figure out (or a just plain too scared to) how to fix it themselves.

Why should the user have to tune it? If the tuner did the job right to start with there should be no user tuning that needs to be done. How many times do you take your factory stock Chevy or Ford back to the dealership to have them retune the FI system? How many of your customers do you want tweaking that 150hp per litre engine? Why would they need to if you did your job?

QUOTE

Doesn't need it. Besides water damage and a couple of the old style coil packs the only failures they've had have been user error. For me 4yrs (2 engines, sold one) and I've never broke down.

Again I guess it is not important because YOU have never had a system fail. Ask EVO owners how it feels to have their AEM system blink out and leave them walking. Bet they wish they had a limp home mode. Can you tune the SDS to handle to handle an overheating condition? What happens if that GM three bar sensor fails? You are left walking with no option, short of calling AAA.

I tune Honda and Acura Engines, Type Fours, VW fours, Turbo VW fours, Some V8s and other engines. With some of the combinations that comes across my counter, I want the maximum control. I can't tell a guy who just sunk 10K into turbo four cylinder that SDS may or may not keep his engine alive. I know Hondata, Motec, Autronic, etc can. I am pretty sure the Haltech system can handle that stuff as well.

For many guys converting from carbs to FI for their older cars it probably is a good way to go, but I won't recommend it to anyone. Just because you have had decent luck with the system doesn't mean it is the best system for everyone. The best system is the one that gets the job done, safely.


In the past I did the basic research into SDS and when I saw that it did not do what I wanted, then went on. There was no reason to do further research.