Performance engine rebuild
01-19-2003, 02:59 PM
#1
Drifting
Thread Starter
Performance engine rebuild
To all those that have been following my engine rebuild, here is the latest update from the engine builder:
Dear Jim:
I've just spent an hour playing with the Tuning Wizard for WinTEC. II've done some sensitivity analysis of the various BSFCs and hp outputs, and here's what I've found:
I don't know how much HP your engine wil generate per liter, but the stock 928S4 with dual pulse (bang-bang) electronic injection generates 65 hp/l. I'm estimating that the TEC II's sequential injection may get you to between 80 and 90 hp/l, if you don't hit fuel pump limits. If you generate just 85 hp/l, you'll have 460 hp at 6500 rpm from your 5.4L engine.
The range of BSFCs for a conventionally aspirated gasoline engine is .45 to .55, and it's set by engine mechanicals, not my choice; I'll just discover what BSFC the engine can support, once it's broken in. Richard recommended we start and.53 and then gradually back it down so as not to risk running lean, detonating and lunching the engine.
At .53 BSFC, your engine would require 36 lb injectors to support 460 hp.
At .47 BSFC, which would about the leanest we could run it once it's broken in, it would take 32 lb injectors.
To stay within the capability of your 24 lb injectors at .53 BSFC, I've had to limit RPM to 4500 rpm, with estimated 330 hp output at that speed. That's okay for the first 500-750 miles of break in, which you'll run at no more than half throttle, anyway, to break it in correctly.
I recommend you drive it within those limits and then do a full throttle partial curve dyno run to 4500 rpm over in Mobile at the end of the first period to see what HP you're generating, having them signal you to abort the run immediately if you generate more than 300 rear wheel hp during the run. The shape and height of the partial curve will tell me what I need to know to calculate the reqired injector size. Then you'll need to buy a set of injectors properly sized to the engine; they're going to cost you about $80/injector. I think it will take at least 32 lb injectors, 36 lb injectors with a greater safety factor, but we need to know for sure. Injectors too big are almost as bad as injectors too small. I've downloaded the Tuning Wizard onto my desk computer and I'll be able to calculate the proper injector size once we get that value.
Here is a recent pic of the project: <img src="http://boards.rennlist.com/upload/928engine_WEB.jpg" alt=" - " />
Dear Jim:
I've just spent an hour playing with the Tuning Wizard for WinTEC. II've done some sensitivity analysis of the various BSFCs and hp outputs, and here's what I've found:
I don't know how much HP your engine wil generate per liter, but the stock 928S4 with dual pulse (bang-bang) electronic injection generates 65 hp/l. I'm estimating that the TEC II's sequential injection may get you to between 80 and 90 hp/l, if you don't hit fuel pump limits. If you generate just 85 hp/l, you'll have 460 hp at 6500 rpm from your 5.4L engine.
The range of BSFCs for a conventionally aspirated gasoline engine is .45 to .55, and it's set by engine mechanicals, not my choice; I'll just discover what BSFC the engine can support, once it's broken in. Richard recommended we start and.53 and then gradually back it down so as not to risk running lean, detonating and lunching the engine.
At .53 BSFC, your engine would require 36 lb injectors to support 460 hp.
At .47 BSFC, which would about the leanest we could run it once it's broken in, it would take 32 lb injectors.
To stay within the capability of your 24 lb injectors at .53 BSFC, I've had to limit RPM to 4500 rpm, with estimated 330 hp output at that speed. That's okay for the first 500-750 miles of break in, which you'll run at no more than half throttle, anyway, to break it in correctly.
I recommend you drive it within those limits and then do a full throttle partial curve dyno run to 4500 rpm over in Mobile at the end of the first period to see what HP you're generating, having them signal you to abort the run immediately if you generate more than 300 rear wheel hp during the run. The shape and height of the partial curve will tell me what I need to know to calculate the reqired injector size. Then you'll need to buy a set of injectors properly sized to the engine; they're going to cost you about $80/injector. I think it will take at least 32 lb injectors, 36 lb injectors with a greater safety factor, but we need to know for sure. Injectors too big are almost as bad as injectors too small. I've downloaded the Tuning Wizard onto my desk computer and I'll be able to calculate the proper injector size once we get that value.
Here is a recent pic of the project: <img src="http://boards.rennlist.com/upload/928engine_WEB.jpg" alt=" - " />
01-20-2003, 03:31 AM
#3
Jim,
O.K., I'll bite...
What's going on there?
In particular what's that up front, coil pak's, management, ???
Is this the same 79my, 88 S4 block with the 944 heads, and 104mm J&E slugs you posted about last January. What happened? Were there more mods, a frag, or, a huge delay?
Very clean.
John S. and Pattycakes
O.K., I'll bite...
What's going on there?
In particular what's that up front, coil pak's, management, ???
Is this the same 79my, 88 S4 block with the 944 heads, and 104mm J&E slugs you posted about last January. What happened? Were there more mods, a frag, or, a huge delay?
Very clean.
John S. and Pattycakes
01-20-2003, 10:17 AM
#5
Rennlist Member
Hi Jim,
Looks like an interesting project !
Is it using an LH MAF ? Is so, I don't see how you will get it to produce much more power than stock, unless your engine management system can cope with > 5v output from the MAF.
It's pretty well up to 5v with a stock 5.4 engine.
Bigger injectors won't fix that.
Looks like an interesting project !
Is it using an LH MAF ? Is so, I don't see how you will get it to produce much more power than stock, unless your engine management system can cope with > 5v output from the MAF.
It's pretty well up to 5v with a stock 5.4 engine.
Bigger injectors won't fix that.
01-20-2003, 11:21 AM
#6
Drifting
Thread Starter
John,
Yep, same motor but project has taken much longer than expected.
Jack,
Tec II.
John,
No, it is using a Tec II with a MAP sensor.
"Is it using an LH MAF ? Is so, I don't see how you will get it to produce much more power than stock, unless your engine management system can cope with 5v output from the MAF.
It's pretty well up to 5v with a stock 5.4 engine."
I'm not sure what you are talking about? The engine has extrued honed Euro S intake, 5.4L (104 mm) J&E forged pistons, Devek cams, 944 1/2 heads, Devek Jet Hot coated headers, ETC, ETC.... Not stock!
Yep, same motor but project has taken much longer than expected.
Jack,
Tec II.
John,
No, it is using a Tec II with a MAP sensor.
"Is it using an LH MAF ? Is so, I don't see how you will get it to produce much more power than stock, unless your engine management system can cope with 5v output from the MAF.
It's pretty well up to 5v with a stock 5.4 engine."
I'm not sure what you are talking about? The engine has extrued honed Euro S intake, 5.4L (104 mm) J&E forged pistons, Devek cams, 944 1/2 heads, Devek Jet Hot coated headers, ETC, ETC.... Not stock!
01-20-2003, 02:36 PM
#7
Rennlist Member
Hi Jim,
My point was that the MAF could have limited the performance potential of the engine.
I have no doubt that you will get more power with those mods, and an engine management system to suit.
Do the 944 heads have larger valves as standard ?
Let us know how the project progresses !
My point was that the MAF could have limited the performance potential of the engine.
I have no doubt that you will get more power with those mods, and an engine management system to suit.
Do the 944 heads have larger valves as standard ?
Let us know how the project progresses !
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01-20-2003, 05:25 PM
#8
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kblair/Jim -
HEY - you get a few miles from me (Pensacola) and don't let us know?!?!?
We actually had an autocross scheduled for yesterday (unfortunately - it got cancelled!). Coulda been fun! If nothing else, a 'mini-parade' of 3 sharks at the beach could be pretty cool!
BUT - Next time your nearby, drop me a note!
HEY - you get a few miles from me (Pensacola) and don't let us know?!?!?
We actually had an autocross scheduled for yesterday (unfortunately - it got cancelled!). Coulda been fun! If nothing else, a 'mini-parade' of 3 sharks at the beach could be pretty cool!
BUT - Next time your nearby, drop me a note!