Building a Motor, how to figure out what you can do...

http://www.crank-scrapers.com/

I have one of these, but I have not installed it. Not sure it'll work with my NISMO pan which has some windage stuff built in as well as a rudimentary scraper.

If you read on that site and others it appears that folks can see a couple percent gain, although I'd expect that to be limited at some point. If you have a 1600 hp motor 3% would be 48 hp, but does the 1600 hp motor benefit from oil control that much more than a 200hp version? I guess what I'm trying to say is there should be a limit to how much hp you can gain with one of these in my opinion.

There are more than a few OEM cars that use them. Porsche has them in the bottom of a few pans, as does the big three on some engines, and in some Japanese cars as well. If they spend the money to do it then it is probably worthwhile.

Ron
 
Good point on the valve springs; consider at least checking the valve guides for play as well, if not replacing outright. Rings... I've been very impressed with the effectiveness and longevity of my Total Seal rings. Crank scrapers... yes. I'm using an Ishihara-Johnson (crank-scrapers.com), went in nicely with a little tweaking, very cost-effective. No idea how much it gave me, though - was only a small part of the whole build. My stock pan is otherwise quite good, well baffled and finned.

I would definitely put balancing high on the list, even if limited - I've heard that it's pretty key for inline engines, especially the longer ones, like your 5's and 6's...

Sounds like you ought to consider uprating your cooling system. Many options here. Aftermarket, certainly; in my case, I had my rad re-cored with some kind of performance 3- or 4- row core by a local rad shop - I think the core was for some kind of Ford. It works GREAT - temps rarely go above halfway during full-race conditions in the worst heat - even worse than what we had at Mid-O.

That said, at least for the 924 motors (so very likely for yours, given the common heritage) keeping oil temps down is key to longevity. I run a massive oil cooler - have you any? Mine's the el-cheapo $50 or so 8x11.5" trans cooler sold by Racer Parts Wholesale. I also run a remote filter mount with a Rabbit Diesel MANN or Mahle oil filter (much better than the cheap Fram ones at filtering the smaller stuff). I also run a 3-qt Accusump; with my engine config (long. with a 45-degree layover) oil pressure can be hell on long LH-ers). I suspect you don't have the same kind of problem, or at least not as bad; the crank scraper also helps in this regard, fitting tightly by the low side of the block and providing some additional protection against oil creeping up the RH side of the block. This all also ups the system capacity to 2 gal! :D

BTW, when you say you blew the motor, what exactly was the failure? Loss of compression, headgasket, siezed, spun a bearing???

4 seasons on the motor - did you change the mains or rods in the process? I think my motor wants new rod bearings every other year, aiming to do mains as well this winter. Not sure about lifetime of the rings; they still register 98% or better (within noise of 100% IMO) on a leakdown... need to call my supplier, find out when I can tell I need to replace them...

Another longevity thing I've found, though perhaps your motors are better - my valve stem seals only last so long. Right now it seems to be only about half a season - say 4 weekends. Irritating. Thankfully I have the fancy VW/Audi tool to allow replacement of those with the head on (on-head valve spring compressor) - it's proved its worth, did them just before the IT-Fest. Keep an eye out for oily plugs. The high revs seem to shorten this; if I shift at redline (6500), they go quickly, as they just don't like the revs, whereas my normal 6000rpm shiftpoint may help extend the life. Not something you'll ever really see as an issue on a street car...

HTH...
 
And, I don't feel you can go into these things with an absolute set bufget, like $1000, unless you are accepting that you won't be getting what you want.

Find asecond job, get dreative in the money laundering world, whatever. Do it once, do it right, and don't screw with being cheap about things, especially like guages.

(And I'd leave antifreeze/water IN the engine over the winter, and oil too. )
 
Scrappers and windage trays do work. You have to be careful with the install to avoid oil leaks from the pan as well as checking where the oil pick-up lands up after adding such things.

Interesting comment about Total Seals. They are pricey, but frankly, the only reason I use them is thay can ship you any size you want so that you can file-to-fit--another DIY assembly trick.

BTW, bearings are normally not consumables--unless they were trashed. Obviously rings are as would be rod bolts. If you are rebuilding a motor with an unknown history, you should recondition the rods at the macjine shop to go along with an align hone of the main journals.

Anything you can find NOS on ebay for your motor helps too, such as an oil pump, rockers, cam shaft,etc.
 
We did a new motor over last winter. My original plan was 0.020 pistons, pay for machine work, assemble myself. We ended up with 0.040 pistons due to block condition. A freind with tons of engine assembly experience offered to help out, which I gratefully accepted.

I did not set a budget, but figured it would be about $1k, with my sponsor providing many of the hard parts free of charge. Well we ended up over $1400 for machine shop, but we used a race engine shop (AMT Racing Engines - St. Louis) for this and did not leave any items undone.

A good machine shop, that will use a torque plate is important.

I have always run a windage tray, so can't comment on gains. I have been thinking of trying a scraper though.

The balancing is more important than I expected. The motor spins so much more willingly now, regardless of how heavy stock parts and flywheel are.

We were running a 60k mile street engine (never even pulled the head on this one) before, that had a header, match port (yes I was dumb enough to do this with the head on the motor), correct fueling and timing. The gains were around 14% with the new motor, but peak did not tell the story. The power band drops much less in higher rpms. Peak torque gains were small, but the the curve has a plateau instead of a point at the peak and drops off much slower than before. I attribute these gains to good balancing, don't skimp here IMO.
 
We did a new motor over last winter. My original plan was 0.020 pistons, pay for machine work, assemble myself. We ended up with 0.040 pistons due to block condition. A freind with tons of engine assembly experience offered to help out, which I gratefully accepted.

I did not set a budget, but figured it would be about $1k, with my sponsor providing many of the hard parts free of charge. Well we ended up over $1400 for machine shop, but we used a race engine shop (AMT Racing Engines - St. Louis) for this and did not leave any items undone.

A good machine shop, that will use a torque plate is important.

I have always run a windage tray, so can't comment on gains. I have been thinking of trying a scraper though.

The balancing is more important than I expected. The motor spins so much more willingly now, regardless of how heavy stock parts and flywheel are.

We were running a 60k mile street engine (never even pulled the head on this one) before, that had a header, match port (yes I was dumb enough to do this with the head on the motor), correct fueling and timing. The gains were around 14% with the new motor, but peak did not tell the story. The power band drops much less in higher rpms. Peak torque gains were small, but the the curve has a plateau instead of a point at the peak and drops off much slower than before. I attribute these gains to good balancing, don't skimp here IMO.
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Chris, was it a noticable gain on the track as well?

Raymond
 
I was watching the Rolex series the other evening and they did a piece how they've proven that Audi engines actually lose power with mild engine builds. The curve only turns around once the final pieces are assembled, but unfortunately those aren't allowed in an IT car. ;)

Ray, I thought you said Stephen did a more extensive engine build fairly recently?
 
Ray, for me, the gains between the stock motor I ran in 2003 and the two "IT" motors I've run since then are night and day.
 
The gains were noticeable. In the past we had to get a perfect exit, and a good draft to stay in touch with some of the competition. This year we were able to run side by side down the straight and keep up fine. I would say we were in the lower middle of our pack on power, upper of the pack on handling last year. This year we are in the upper of the pack for power. The Volvo is still stronger, but I can stay in touch. We will find out this weekend at Road America if the Fiero still runs away as we exit T14 the way he did exiting T7 at Blackhawk last year :eclipsee_steering: .
 
Ray, I just made an old Korean lady cry for a half hour at a deposition, so I'm tired of being a lawyer and going to spend 15 minutes of my day with your 1 through 10 ranking list. This is of course "biased" towards my experiences with my car, which is a sloppy, smogged out, low compression late 70s V8. Your mileage may vary, and probably will. But I am probably a bit in the same boat as you that I didn't want to just dial up a builder and have an engine made, I wanted to do as much of it as I could to learn.

So here goes, your top ten, with my rankings of importance (high, medium and low):

1- Pay someone if you don't have the right tools (possibly assemble yourself though)

HIGH. You have to do this otherwise you are itching for disaster. Have the block hot tanked, honed and line bored by a machine shop, at a minimum.

2- New bearings and rings

HIGH -- NO engine rebuild/refresh is serious without doing this. In fact, I would consider this an absolute minimum if I was taking the time to get the motor out of the car.

3- Clean up the valve seats

MEDIUM. Medium in that it is not essential for reliability, but as a part of a good working of the head (port matching, etc.) I would consider the overall work on the head to be HIGH.

4- Deck the head

MEDIUM. The extra compression helps, but it can cause alignment issues, in particular with your cam timing, that could be difficult to solve. I still think the head and exhaust work is more important, by far, than the .5 bump in compression you could get from decking the head.

5- Increase piston size

LOW. The added displacement from an over bore is minimal, or at least was on my motor. More important is to get the bottom end put together right, with good gaps on the rings to save compression, a hone with a torque plate and a good balance for revs.

6- Port match

HIGH. At least for me, I saw significant gains on the flow bench by doing this. Not only are you matching the gaskets, but since you can go in 1" you can clean up some bad early twists and turns in the manifold, and poor casting.

7- Balancing

HIGH. Motor will rev higher, run "smoother" and potentially cooler, and last longer due ot less friction.

8- New parts (what difference does it make beside prevent failure?)

VARIES. Depends on teh part. No need for new pistons or con rods all of the time, on the other hand my motor is notorious for wearing cam lobes so I get a new one for $100 plus lifters every rebuild.

9- Start the expensive stuff, such as balancing as well as flow testing?

HIGH. This small stuff is the "key" to a good IT build. A good IT build is an accumulation of small advantages, which is why it is expensive.

10- Add the turbo or custom ecu

HIGH. Seriously, that ECU is going to get you some gains I think.
 
LOL... I'm pretty sure he was joking about the ECU - I don't think it has much more impact on his car than on mine (as in, no ECU - it's all CIS).

I would disagree about the valve seats - I'd put at least lapping the valves in as a HIGH, as I've seen plenty of motors that flat-out don't seal there... Bit of a waste to do all the other stuff and not seal the combustion chamber. Not sure that a performance valve job isn't also rather valuable, just like port-matching...
 
LOL... I'm pretty sure he was joking about the ECU - I don't think it has much more impact on his car than on mine (as in, no ECU - it's all CIS).

I would disagree about the valve seats - I'd put at least lapping the valves in as a HIGH, as I've seen plenty of motors that flat-out don't seal there... Bit of a waste to do all the other stuff and not seal the combustion chamber. Not sure that a performance valve job isn't also rather valuable, just like port-matching...
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The Valve Job is everything!!! Valve angles have alot to do with how much power you can make. Especially when the valve is not fully open.

Just an example. I have been an ASE Certified Master Technician for over 10 yrs, so I have some experience and skill. I bring this up because I do most of the work other than machining myself. The last engine I did for the Neon cost me less than $2500. That was with a cylinder head that cost about $850.00.
Spend the $, make it right, you wont regret it. Most of the HP is in the head. For every full point in compression ratio you'll see about a 2% increase in power. Not much there in compression unless you go way up. Get the rings to seal, get the valves to close tight, balance the rotating assembly. Run the lightest crank pulley and clutch that you can legally.

or buy the junker until you can afford it.
 
Guys, probably wasn't clear. I was trying to say that just doing ONE item in the head is a medium, if that is all you intend to do. You need to focus on the head and the exhaust in toto; that is a HIGH. That is where the biggest gains are.

On the ECU, didn't the tin man have a brain??? LOL.....kidding, I didn't realize the Audi had mechnical fuel injection.
 
If Audi motors are like VW motors, a .5 increase from 'spec' compression ratio is closer to a 1 or .8 increase. The VWs CR numbers measured lower than advertized during the era of Ray's car. So I would recommend taking a look at this.

The head work is important, but it is important the understand what can and cannot be done. The final result needs to match the shop manual specs - no multi angle valve jobs unless your shop manual specifies one. This does not mean you cannot make improvements over a bad factory job, or worn seats/valves, just that you have a smaller window to work in.

Engine build is definitely a place where it is easy to say "well if I'm doing this much, I might as well take the next step", and for good reason - you are not allowed to do much, so if you want an advantage you have to do it all. Say that half a dozen times and you are 50-100% over your original intended budget, but an IT motor is not a highly stressed peice. It should be a build it once proposition - maybe freshen it after 5 years (I am surprised to hear the 924 needs attention so much more often). I mean what we end up with are just really nice street motors. Keep pressures and temps where they belong and they should live long productive lives.
 
It should be a build it once proposition - maybe freshen it after 5 years (I am surprised to hear the 924 needs attention so much more often).
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You may in fact be right; I just would hate to find out the hard way that I was pushing it too long! With the noted exception of the valve stem seals. Do VW's have the same problem? Can you guys get teflon ones? They shouldn't be all that different...

Very interesting to hear about the VW CR issues...
 
Vaughan,

Does your car have some unusual valve train angles that cause the valve to rock in the guide? It is not normal to prematurely wear out guide seals unless there is excessive side loading of the valve.
 
Build it once? 5 year rebuilds?

Wow...must not run many events. I am lucky to get a season and a half...if that.

If you race a motor it wears out. Rings and bores wear; my cams wear over time. While certainly not on the level of tires or brakes, motors are consumables in a race car.

That is why it is always good to pick-up some mechanical skills and also abide by the philosophy..."a pair and a spare".
 
Vaughan,

Does your car have some unusual valve train angles that cause the valve to rock in the guide? It is not normal to prematurely wear out guide seals unless there is excessive side loading of the valve.
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It's all stock, and good new parts - guides, valves, etc. I don't know if there are unusual angles, or what "unusual angles" would constitute, either. George (Mazuro) warned me of the valve stem seals after I brought him my first set of plugs that, unbeknownst to me, were fouled by dead stem seams. He recommended teflon ones, but sadly, though they're available for the 944, the 924 ones are larger and not interchangeable. :(

Oh, yeah - I typically run at least 6 weekends per season - yes, may be higher than most.
 
It hasn't been asked yet, but any good books out there detailing the building of a "race" engine?

I've rebuilt a lot of stock engines (air cooled VW's and Porshe's) but that is pretty basic stuff. Check the tolerances and replace if out of spec.

Any recommendations or reviews of books?

Thanks,
Jim W.
 
Jim, they are probably marque specific. I've got one for Rover V8s from the UK, I know Ron Earp has a NISMO book for his 260z. Do some google work and see what is out there for your motor.

Also, someone above said it and it is true. Different motors respond better and allow more improvement in different areas. Compression bump in my motor is a bitch because of the V design adn because I can't do it with the pistons. But, my heads are extremely poor castings and the head work I had done showed real gains. Other cars really benefit from careful exhaust work (RX7). Etc.
 
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