Engine rebuilt + search for more HP...

[Johan123m]

Hey,

It's time for a rebuilt of my 2.4T engine (mfi) and like a lot lot of folks I would like to gain some extra hp...hehe
I would like to keep the mfi (it needs to be rebuilt anyway) and have a nice revy engine
I've done a search and I've gathered a lot of info. What about the following:

Original Mahle 2.4S-P&C's
S-cams
rebuilt MFI-pump to s-specs
rebuilt throttle bodies to s-specs
porting of heads to 36mm
Basicely...make almost an S out of it...

If I buy the new Mahle cylinders, do I need to install an extra oil-cooler. Will they give me the same compression ratio as an original s-engine?
Are there any changes to the case (5R) necessary?
Are there any changes to the crankshaft &r ods necessary?
Some people tell me that enlarging the ports isn't really needed...
What's your opinion?
Am I forgetting anything?
There are probably a few cheaper ways to achieve the same hp, but isn't this more durable?
What about keeping the original cylinders and install 2.2 pistons with s-cams? In this case, should I also rebuilt the mfipump to S-specs or keep it just stock?


Thanks for your advice!
Johan

[Eagledriver]

The previous owner of my car did a similar thing as this. I'd do the things you said except I'd put in 90mm Mahle pistons and cylinders for a 2.7 rs replica engine. I'd also buy a 7R case (they can be found for about 500 dollars). You may find a case with the timecerts and new studs already done. That's what I did for my engine. Most 7R cases are bored for the bigger cylinders already.

This rebuild is going to be very expensive due to all the MFI work involved and the porting of the heads.

-Andy

[eapcpa]

"This rebuild is going to be very expensive due to all the MFI work involved and the porting of the heads"

Tell me about it. I am afraid to add up all of my receipts so far.

[Johan123m]

I thought the 7R case would only bee needed if I wanted a bigger displacement (2.7-2.9)? Wasn't the original 2.4S also built on a 4R or 5R case?

Could someone tell me from reading my original post if I'm missing something. Also a total estimate on machine work would be welcome....

About costs. This is what I I found so far:

original Mahle 2.4S P&c's: about $3000 (I buy them in Germany)
Rebuilding MFI (pump/stacks/...): about $2500
2 used s-cams: about $600 (would it be cheaper to regrind the T-cams?)
All gaskets, bearings&stuff needed for a rebuilt: $800
40 hours of labor
All the machine work: NO IDEA...what would be the costs if we're going from a worst-case-scenario (resurfacing crank - rods - enlarging ports - rebuilding heads - regrinding cams - etc)
Am I close if I would say $2500???

What am I forgetting? What about the distributor? What about an extra oil-cooler?

And of course, last but not least, what would you do differently!

Thanks for your feedback! Much appreciated!!!
Johan

[Zendalar]

U sure you want to do that engine?

I mean, with that much money, you could buy way better engine..

[Johan123m]

Hey Zendalar,

What do you mean...a more recent engine like a 3.2 or do a 3.6 conversion? I don't want that because I want to stay period-correct.
The only thing I want to consider is a 2.7 rs-specs engine, but it will be even more expensive because I need the R7-case and more machinework.
Anything in between 2.4-2.7 I'm interested in, si if any of you have a great set-up around 180-200hp that would be cheaper an d reliable...please let me know!

I'm still thinking about the 2.2 pistons...

Regards
Johan

[rvanderpyl]

If you go to a 2.7 along with a new case you will also have to have your heads cut to work with the 90mm cylinders, thus more money.

If you have not taken the motor apart yet than you can't be sure of what you need. IE your case may need so much machine work that you might as well get a 7R case and go bigger, or perhaps your cylinders are fine and you can just get some S pistons (or JE's), there are way to many options possible, especially when you do not know what kind of shape your current parts are in.

As for buying another motor, that is always the suggestion when the total cost of a rebuild comes up, but as many people have pointed out, you are buying a used motor, no guarantee that you aren't going to have to rebuild it sooner than later.

Although after I sat down and made up a spreadsheet with the costs of what I have bought, and what I still want/need it would make way more sense to sell everything and just buy a newer car. But since when has an old Porsche been about making sense?

[shbop]

Couldn't have said it better!

[Eagledriver]

You can use the 4R or 5R case for any of the engines you mentioned. I'd spend the 500 dollars or so to get the 7R. This is especially important if you plan to use aluminum cylinders as opposed to the Biral that you have now. I suspect the new 2.4S P/C set will be nickasil (aluminum).

If you are going to use aluminum cylinders then you might as well go with 90mm for a 2.7. If you then buy a 7R case you should be able to find one from a 74-77 that is already bored for 90mm cylinders.

You can build with your old case but they are more prone to cracking. If you can find some biral 2.4S cylinders then you might as well keep your old case as it should be fine.

-Andy

[Johan123m]

Guys,

Thanks for your replies. Anymore feedback is welcome!
Some estimations of machinework (going from a worst-case-scenario - resurfacing case, crank, headwork, etc...)?

Can anyone tell me what's the difference between a 0R and a 5R-case?

Thanks!!!!
Johan