Wayne's Answer to the Question: What engine should I build?

[Wayne 962]

This is indeed the most commonly asked question. Many people have different answers. For me, the answer is very clear:

Set your budget, then build the largest power engine you can build within that budget.

People make rebuilding decisions that don't always make sense to me. For instance, they'll rebuild a 2.7 engine and have the cams reground, but not to 2.7S specs. Or they will buy new pistons and cylinders for the 2.7, but not the 2.7S spec, when the costs are the same. You're leaving extra HP on the table.

How about a 3.0 rebuild? Running the euro pistons to increase compression and regrinding to 964 specs is a no brainer if you're buying new pistons and cylinders, and regrinding your cams anyways.

Rebuilding a 2.4S? Installing the 2.2S pistons is a great upgrade that increases compression and power - with little additional cost, particularly if you're replacing your pistons anyways.

MFI systems can be a bit difficult to recalibrate, but if you're running carbs, there's no reason not to bump compression and run hotter cams.

All 3.0s should be increased to a short stroke 3.2 if you're buying new pistons and cylinders. Cost difference is very little. 3.2s should go to 3.4s - again, costs are minimal.

My basic point is that most rebuilds cost about $6-$8K, whether you rebuild a stock 2.2T or a 3.2 short stroke. You should look carefully at what you have, and then maximize the power out of it. Nothing beats displacement, of course. Hotter cams are always good if your fuel system can adjust to it, and smog laws aren't a concern. Bumping compression is also a good way to gain cheap power - the RS spec is too low at 8.5:1 - you're leaving power "on the table."

If you're planning on rebuilding a 2.2, for example, you might want to consider instead buying a used 2.7 and rebuilding it instead (cores can be found quite readily for $500-$1500). Put your original motor in a corner of your garage and spend the $$$ to build a higher-compression RS-spec engine and maximize the power for your $$$.

Just some thoughts to kick around...

-Wayne

[emcon5]

I think you missed a word,

Originally posted by Wayne at Pelican Parts
but if you're running carbs, there's no reason not to bump compression and run hotter cams.

Fixed.

[asphaltgambler]

We are not worthy

[Jeff Alton]

Thanks Wayne, good input. Yes, I did recently ask that same question!
3.4/3.5 twin plug it will be then!

Jeff

[dd74]

Excellent stuff, Wayne. Maybe you should write a book.

Given your suggestions of bumping up compression and more radical cams, at what point would you suggest EFI over carbs, or vice-versa?

[NevenM]

dd74

I'd always choose EFI over carbs for a custom engine, Both cost about the same (2K minimum) but EFI has potential for more power from the same engine, IMHO

Neven

[H.G.P.]

The problem is.....originality. (for my 69 that is)

[dd74]

Originally posted by NevenM
dd74

I'd always choose EFI over carbs for a custom engine, Both cost about the same (2K minimum) but EFI has potential for more power from the same engine, IMHO

Neven

Neven - I must be looking on the wrong web site because the only EFI system I've seen (in its entirety) is going for close to $6K. The last time I looked at PMO (Weber-like carbs), the entire kit was $3K.

Do you know of someplace else to look?

[NevenM]

dd74

My 2K EFI System.
http://www.bitzracing.com/products/Complete_kit/index.html
$1600, 2nd Hand MFI TB's and Plastic Stacks approx $200, Bore
TBs to 36mm and Bore Stacks $200, Ok this assumes you have
MFI Heads, If you started with a CIS System you only need the bitzracing kit, but I think EFI on a set of MFI TBs & Stacks would look cool

Neven

Neven

[911SCfanatic]

Neven, where did you get the tbs and stacks bored so inexpensively? I assume you had to rebuild the tbs at the same time with new plates, etc.

[NevenM]

Bill

Jeff, JHines9146@aol.com does the stacks for $150, I can do the TB's myself, As for rebuilding the tbs, this depends on the condition of them, Onece you clean them up the most I'd look at doing is shaft bearings if they are excessively worn, The ones on my 2.4 which had 70K miles were fine, A lot of the 2nd hand ones probably haven;t done much as they have been sitting in garages since they were ripped of the motors when the first mechanic couldn't understand the MFI touched it. A lot is made of rebuilding TBS in my experiance it really means setting them up again and undoing what a number of tuners have done

HTH
Neven

[gumba]

Where can you find 2.2S p&c?. I've seen one set for sale on the Pelican site a long time ago. Carquip sold a set for $1450 on Ebay recently.

[911SCfanatic]

Neven, thanks for the info. From the info I had previously, getting stacks and tbs bored was *expensive*. For example, Eurometrix charges serious $$. I'd like to know the differences, if any, between what Jeff does and what Eurometrix does. I know Eurometrix bores them by hand--like porting heads.

[Wayne 962]

Originally posted by dd74
Given your suggestions of bumping up compression and more radical cams, at what point would you suggest EFI over carbs, or vice-versa?

EFI is obviously a supior choice to carbs, but even the best EFI systems can only do so much. The engine's power is mostly dictated by its mechanical components. You can jet a set of Weber 40s or 46s to run just about anything. EFI is a great and fun toy to play with, but the price is high ($6K for the full independent throttle-body (ITB) setup). If you can afford EFI, then go for it all the way, however, the $$$ per HP gained is not that great, because of the high cost.

One advantage with a system like the TEC-3 is that adding an engine management system allows you to easily run a twin-plug setup. Running 2 sets of plugs will run you about $1500 no matter which way you slice it. If you get a full TEC-3 setup, the cost difference between a twin-plug setup and a single plug setup is merely the cost of an extra set of coils (around $100 I think). Another added benefit of the system is that it can be used on any car, and can be easily changed as the engine is modified.

Not sure if this answered your question?

-Wayne

[Wayne 962]

Originally posted by NevenM
I'd always choose EFI over carbs for a custom engine, Both cost about the same (2K minimum) but EFI has potential for more power from the same engine, IMHO

Yikes, you're a little off base there. A good used set of Weber 40s which will run any street engine up to 3.2 costs about a $1,000. An EFI setup with ignition will run about $6K when you're done. Big cost difference there.

-Wayne

[dd74]

Yes, Wayne: that pretty much answered my question. I'm just on a fact-finding mission for now.

So 3.2 is the maximum for both sized Webers? 40s and 46s?

[Wayne 962]

Originally posted by H.G.P.
The problem is.....originality. (for my 69 that is)

Blah, blah, blah...

Take your stock engine, and put it in the corner of your garage. You want 1969 originality, you're going to get 1969 performance and reliability.

The cars are much more fun to drive with more power.

-Wayne

[Wayne 962]

Originally posted by dd74
So 3.2 is the maximum for both sized Webers? 40s and 46s?

No, sorry if that wasn't clear. Weber 40s can handle up to a street 3.2. A race 3.2 and anything bigger should use 46s.

As for the MegaSquirt stuff - I haven't had any experience with it. It seems like it would be a improvement over the CIS, however, a good, running CIS system is hard to beat. As I said previously, you'll get the most power out of mechanical changes to your engine - the fuel system only serves to best delivery fuel to that mechanical system efficiently.

If you bolt on this MegaSquirt system to a CIS motor, then you'll be hard pressed to see significant HP gains, as you will be limited by the mild cams and pistons in the engine. Yes, the system will probably delivery fuel much "better", but it will be like putting titanium rims on a bicycle - you're not going to gain a tremendous amount of speed.

The thing I don't like about MegaSquirt is that it doesn't have integrated ignition (yes, there are aftermarket kits that add-on ignition, but it's not part of the regular open-source software). Ignition / Fuel mapping is very important and probably the main feature of engine management. Yes, I would probably say that if you're thinking of placing carbs on a CIS stock engine, then you should consider this solution. However, for a custom, performance engine - I don't think it's quite there yet. The TEC-3 with ITBs is what I recommend currently.

-Wayne

[NevenM]

Wayne

In some ways you have preempted my reply, The ignition issue is irrelevant in a Carb v EFI comparison.

What I attempted to convey was that you could put together an ITB EFI solution for much less than 6K. I did not advocate bolting EFI onto an unmod CIS Engine. On this subject if you did want to do a performance upgrade on theses engines (and they are begging for it) because of the Piston/Cam/Induction interdependability you have to change all three, I agree with you anyone who buys a new set of CIS P&C is not doing a performance rebuild, They must be doing it for originality reasons. If you had Nikasils then you have the option of JE's else a number of P&C Sets. JE's are more than suitable for a street engine, they will be noisier than Mahle when cold but unless you are building a race engine the extra temp/stress on them in an air cooled engine is well within their capabilities. But lets face it these are not quiet engines.

Having changed the Pistons you may choose a cam to suit.
This finally leaves us with induction, Since the CIS will not handle anything other than mild cams your choice EFI or Carbs, As you can guess I'd advocate Megasquirt EFI with the original intake for the following reasons.

1/ It is cheaper than Carbs and more configurable
2/ It can be upgraded to ITBs later on
3/ The Megasquirt ECU is one of the least valuable items in the whole setup, If you feel the need you can change it for a TEC-2, MOTEC, Haltech etc later on without a great cost

The only other suggestion I'd make is to twin plug the heads even if you don't immediately have the budget for the ignition controller, it fits with point 3

Neven MacEwan
B E E&E
1973 911E (Eva)
1970 914/6 (Eric)

[David]

Wayne,

After looking at your engine choices in the book, I wonder why the turbo engines are relatively stock. I.E. stock cams and CIS. I would think people that are building a turbo engine have a larger budget. In the next printing how about have a turbo set up for mid range power and a turbo set up for top end power. JMHO.