2.4T MFI - Not a complete dog?!

[Tim Walsh]

I have a 73 with a 72 engine, but I also have an extra 69T longblock.

I think it will require about 4K for the basic rebuild plus 1K for the MFI rebuild 400 for porting another 1K for pistons 300 for boring the cylinders and another 800 or so for new cams. If I go with the hotrod engine I'm going to try to budget about 8K.

John,
I had forgoten about the smaller stacks and throttle bodies but I do think Warren has mentioned that it will take about 10HP off the top end at least for use in a 2.7RS engine. Porting the heads wouldn't be a big deal, it's about 300 to do that at my local porsche shop. I'll have to find out if boring the stacks will work or if I'll need to get magnesium stacks.

I'd like to use MFI if I can for this engine but I'm not opposed to running EFI either.

[zotman72]

To do a significant upgrade of performance on a 2.4T motor, it takes serious money. A couple of 2.2 Pistons and sport muffler might buy you 20 more ponies. Beyond that, open your wallet.
Porting, case work, proper components (cams, stacks, throttle bodies), P/Cs it all adds up. Get Wayne's book and drool. Determine where your $ ability resides and add 40%. Oh, when I built my 2.4S motor right, it was about 5K and I did the assembly. HTH

[Tim Walsh]

I will be doing all the non machine work myself so I know that will go a long way to lower the costs, but I will have to buy the specialized tools.
Bill,
What did you do with your MFI other than recalibration?

[billwagnon]

The PO of my car had the 73 T engine rebuilt with 9.9:1 S pistons, S crank, and E cams. Receipt from 911 Engine Company in CA was just under $6k in 1999.

It's the fastest Porsche I've ever driven. Heck, it's the ONLY Porsche I've ever driven.

[zotman72]

I swapped my T pump for an S pump as part of the deal I made with my wrench, he needed a core for an RS engine he was building. Your injectors of course are the same. You can port your heads and throttle bodies with a dremel if you are brave. I was not that brave.

[Tim Walsh]

Billwagnon,
Did the car already have the webers on there or was the cost of the webers included in that price?

[billwagnon]

I think probably what happened was the Webers were received in trade for the MFI parts. They were used Webers; they've been fine for me but the shop I took it to for carb adjustment said the butterfly pivots were a little worn.

The rebuild was also 4 years ago now. I haven't been able to find out anything else about the 911 Engine Co. (cool name!) in Novotny, CA. Apparently the guy running the company (and doing the work) developed a bad reaction to solvents and had to close up shop.

[Tim Walsh]

Hmm.. I'd really like to keep the MFI.. It just sings to me like nothing else. but 5k to go from a S longblock to an S longblock is mighty tempting

[jluetjen]

Tim (l33t9eek)
My point was that the biggest you could go without cracking the case would be 2.5 (85 mm bore x 70.4 mm stroke) and something like 180-190HP. If you want to go up to 2.7, figure something like another $2k to the costs of a 2.4/2.5S to have the crankcase reworked. The result of that $2k would be 20 to 30 HP over the 2.4 or 2.5S depending on the CR and the porting of the heads/throttle bodies.

[Tim Walsh]

AHH ok I think I've got what you mean now but I think with as unknown as this engine is wouldn't it be much better in the long run just to go ahead and crack the case? Since I have a 3R/4R I'm definitly leaning towards the 2.5S.

[jluetjen]

Tim;
I'm in the process of disassembling a 7R engine now to be ultimately reassembled as a race motor. The big thing that I've gotten from the dis-assembly, Wayne's book and a recent conversation with Walt, is that it doesn't really matter how OK a case is in it's present condition, once you've cracked it it will warp about 80% of the time, which requires it being R&R'd to the tune of almost $500. Even if you are careful (as I was) and use a lot of heat to remove the head studs, there's a good chance at least one of them will strip. Once that happens, you're into ca$e-saver$ or timecert$. Then you might as well do the the oil-by-pass mod since your in there. Throw in a wash of the case, maybe R&R the oil gallary plugs, etc. etc.

[Jim Richards]

Given the amount of additional money to make an S, an E with 85mm P&C's and a 9.5:1 CR might be a great compromise.

So, what kind of $$ would it take, if you're starting with a 2.4L E engine (7R case)? Just dreaming now but you never know...

[jluetjen]

Jim;
My guess -- the price of boring the iron or Byrol cylinders out 1mm and new 85 mm 9.5:1 CR pistons from JE and you're there (plus any freshening of the heads such as a valve job). I suspect (but don't know for sure) that you'll be able to adjust for the additional 4% in capacity with the part-throttle adjustment on the MFI. I'd think that the 3-D cam should be fine since the engine's cam isn't changing.

[Jim Richards]

Thanks for the feedback, John. For a 20 or 30 HP increase, that might be a nice cost effective mod as it'll be a while before my wallet (and my lovely CFO) recover from the current projects on the 73E.

Tim, if you build this 2.5L, let me know and I'll drive down to see the FT really fly!

[jluetjen]

Oops. Just to clarify, taking a 2.4E up to 2.5 plus the extra 1.5 of CR won't get you up to 180-190 HP. I'm guessing more like 175 +/-. If you put an S cam in and don't touch the heads, you might be up 185-190, but you'll have less torque then an E below 4000 RPM and not as much torque as a real S above 6500 RPM. If you open the intake ports up to 36 mm, and BTW maintain a similar profile to the inlet tracks as a real S, and go up to 2.5 liters with a 9.5:1 CR, you'll most likely be in the 190-195 HP range.

We were discussing at least 3 different configurations.

[Jim Richards]

John, let me see if I'm followng this correctly...let's say I want to get up to "S" HP (~190 HP) but want to have the nice "E" torque over a wide RPM range. If I bore 1mm, put in 9.5:1 85mm pistons, open my intake ports from 32mm to 36mm, bore out my MFI stacks & throttle bodies to "S" specs (is that what you meant by "maintain a similar profile to the inlet tracks as a real S"?), adjust my MFI pump (E space cam), and do a valve job while I'm in there, that should pretty much cover it?

Oh guys, sorry I hijacked the thread. This was supposed to be about T's. I just got carried away.

[jluetjen]

...let's say I want to get up to "S" HP (~190 HP) but want to have the nice "E" torque over a wide RPM range.

Given the same engine size, you can't have both. You can either get the big S HP (at 6500 RPM) or an E's torque at 3500 and below. You can't have it both ways without increasing the capacity further.

If I bore 1mm, put in 9.5:1 85mm pistons, open my intake ports from 32mm to 36mm, bore out my MFI stacks & throttle bodies to "S" specs (is that what you meant by "maintain a similar profile to the inlet tracks as a real S"?),

What I meant was that you can't take a set of 32mm T/E heads and just bore out the intake passage to 36 mm and think that you're done. Both heads actually have a profile that starts at either 32 or 36 mm at the manifold face, and EXPANDS by about 1 mm for each 1/2 inch in from the manifold face. At 1.5 inches in from the manifold face, the S heads have opened up to 40 mm's while the T/E heads are only opened up to 35 mm. This expansion I suspect is important to slow the intake air down as it goes around the valve guide bosses and around the corner to the valve. From what I can tell, the profiles of the intake ports are similar, it's just that the S ports proportionally larger.

...adjust my MFI pump (E space cam), and do a valve job while I'm in there, that should pretty much cover it?

If you're changing engine cams, I believe that you'll need the 3D cam in the MFI pump changed to match the engine cams. If you take a look at the fuel delivery curves for the E versus the S (I've seen the 2.2 charts, they're in the shop manual on the HP charts), the curve for the S is significantly different from the E, since an S needs significantly more fuel above 4000 RPM then the E. If I can dig them up tomorrow I'll try to post them.

[Jim Richards]

John, I was acually thinking stock 2.4L E --> 2.5L, with 9.5:1, keeping E cams, E MFI space cam, and doing some headwork. An alternative is to upgrade to sort of 2.7RS, keeping the E cams for broader torque at the expense of HP. I'm saying more than I actually know here so please go easy on me.

Of course this is just on my wish-list for next year.

[Tim Walsh]

Thanks for the info.. it's pretty daunting to think about tearing down my engine and doing all this work.

So what I'm hearing is that it's actually best to avoid splitting the case if at all possible? It would definitly save some $$ but I'm more worried about building my motor up right even if it has to sit a little bit longer while I work up the money.

Jim,
Is there enough iron in the biral cylinders to bore them out the extra 1mm? I know T cylinders do I just wasn't sure about the Fe/Al cylinders. When she's back on the road you're more than welcome to come by and drive her. Or maybe I should drive her up to a NOVA run...

[Jim Richards]

Tim, I'm not sure about being able to bore the E's cylinders 1mm, but I'll start asking around. If this is a 15 HP bump from the E's 160HP, I'm not sure if I want to plan for this mod or for a 2.7RS upgrade further down the road. I do know that at some pont I'd like to uprate our E engine.

It would be great if you can make it all the way up here for a NoVA fun run. They're always a great romp through the countryside. There's plenty of room in our house if you need a place to stay overnight.