Thread: Thoughts on a full race motor setup

Piston design is more than just you sending in your sr16ve piston and wanting it +4mm bore and 2.5mm higher piston pin with .100" deeper valve reliefs. There are a number of other factors that affect performance besides those. Weight is a major factor in high RPM power as well as longevity and engine wear. Now I am not going to give out all the secrets here ofcourse but most people do not know that you can make a 92mm piston lighter than a 84mm piston with the right design and "options" ofcourse. But most people do not know what all you can do to a piston when making "custom pistons". The average Joe just wants to spend as little as possible, sometimes not even considering how much power another few hundred $ could do for you, they would rather save $1 if they could. As piston speed increases, the engine moving components are acted on by friction as well as taking more power to continue to make the engine run while outputing "x" amount of power.

I have done 1 back to back comparison of piston design on power output. This was because someone got some "shelf" pistons that had 13:1 compression " stated" compression ratio and they were trying to run the motor on pump gas which didnt turn out too the best. The engine never blew up, it just didnt make the power on 92 octane as it was expected. The peak power was also around 8200rpm and it was thought to be more around 9000rpm. I was called upon to "spec out" a new set of pistons for them to replace their current ones. They bought some shelf stock CP's for $485 originally. The CP pistons that I got for them were $770, a $285 increase over their "shelf" ones. these pistons were spec'd for only 12:1 compression, and the whole piston was redesigned for weight savings where it could be. This motor is near 6000fpm at 9000rpm so any little weight you can save will help a lot.

When these pistons arrived (8 weeks later) the engine was removed from the vehicle and the block re-honed. Then pistons swapped over, and the engine was re assembled and installed. All in 1 day or so with 2 people working on it ( myself included). The next day it was broken in again and then retuned.

In the end, with 35psi less cranking pressure, this custom set of pistons made 7 more LB ft TQ and 24whp at 8800rpm. Some of this power gain was because of a better done design for better flame travel but most was the 269 gram new piston vs the 345 gram "shelf" piston. That is 75 grams in weight savings or about 22% lighter.

There are many options for piston design. Most of it you need to know the limitations of the motor itself, and the parts you are going to use. And as well, you need to know what your cylinder head can do and what its specs are, your combustion chamber as well as the valves and so on.

Next time you order pistons, ask a feq questions about your options.

The same goes for Connecting rods. Most people will put 600 gram Crower Pro series rods in a little 2.0L motor for NA use. Personally if you were going to do that, you better be spraying a nice healthy shot of Nitrous on it. Again, a custom con rod can weigh 25% less than a shelf rod, and yes it will probobly cost another 25% more too.

-Ted

Honestly depending on your headwork, intake manifold and header you may not have been making anywhere near 225whp. Not trying to burst your bubble, but 215-220whp is about the limit on good stock parts. Now i'm not sure on your cylinder head work, but i do remember you saying that you were using Franklin STG3 cams and that is one of the reasons behind my statement. Your motor was probobly making another 20lb ft TQ through the midrange, so you were making about 10-12% more HP through that point. But Your HP will peak early and flatten off with a larger motor if the induction system isnt up to par.



I have a few secrets here and there that I wont post publicly but taking the shine off the top of the piston and removing any sharp spots or thin areas is very critical. you can actually have your piston manufacturer do this but it usually costs about $80-100 per piston, thus most people do it themselves.



Coatings are great, There are 3 main coatings that you can do to the piston. The ceramic coating on top is great for keeping heat out of the piston, great for Turbo or Nitrous applications. Also a teflon coating on the piston ring lands and skirts. Most companies dont do this much other than one or two. Mahle has the nicest coating I have seen on the skirt. I have pulled apart 100,000 mile 911 turbo motors and that coating is still there and no excess piston or cylinder wear present. The last coating is a sort of teflon coating on the bottom of the piston. This helps keep oil from sticking to the piston. This is also a great coating to get done to the crank and rods as well. It can get pricey but in an endurance motor making every last HP, it is a necessity.

-Ted

that is just plain stupid! In a high psi turbo application, yeah they are great rods very stout, but for a high reving na, a much lighter rod would have many more benefits

Intake manifold is a stock 20ve manifold with stock throttle body, Again the manifold was slightly ported and port matched to the head. There is definetly a crapload of torque down low thats for sure. The car pull soo hard from even say 3k all the way to 8k and its still definelty making and possibly increasing in power at 8k. Definetly felt like it pulled harder from 7k-8k than my stock 20ve cam w/boltons.

I was impressed to say the least at how well it pulled down low. It was almost like putting myself back into a turbo sr, lol ok not quite but definetly a better all motor feeling than just relying on upper rpms to make good power

I know a lot of people have claimed to have "issues" with the arp head bolts, I haven't. 26psi max on this motor so far and no problems with the arp2000 head bolts torqued to 105ftlbs. I don't know if head bolts are going to be much of an issue, especially on a 300hp motor.

I get a huge discount at work, so I may buy a MSD streetfire ignition for $115 with adjustable rev limit. I will be getting springs and revving to 8K.

Motor has over 11K miles on her now. Aside from the timing cover gasket leaking slightly there are no issues. I will be fixing the leak when the new mani goes on.

My goal is peak torque at 5000rpm, 200whp by 3500rpm, and 500whp available for 2000rpm, and at least 90% of peak power available at 6000rpm. The new flywheel and clutch (dyno in 4th), exhaust cutout, and TS mani should have huge gains from 3000-4500rpm. All my dynos in 4th gear resulted in 200whp available at 3800rpm, but in 3rd (clutch slipped in 4th) 200whp was avail at 4500rpm, and 4000rpm with exhaust disconnected.

Ultimate goal is 400whp on pump gas 16psi. 500whp with the meth/water injection and pump and 22psi.

i agree on the pistons and i have also seen where this makes a decent gain, even so more with the rods....the question is who is going to spend the money needed to to get the pistons internally milled and " matched" to the combustion chambers.. using cp to get a x design to lessen weight that is 1000 easily into pistons...

the most i have ever spent on pistons for a customer is $905. those were billet machined pistons after completion. on a max performance na motor it is cheap power.

as for the arp studs. the tenstile strength of the stud changes with temperature. they are also undercut so if they are tigtened higher than spec, it doesnt take much for them to stretch.

-Ted

This is something i've always wondered about and since there is so much info flying around it seems like the time to ask it.
If you were to get custom lightweight rods and pistons made and say for arguments sake the piston was 20g lighter than the standard piston and the rod was 10 g lighter than standard and were were going to lighten the crank would you aim to car 30g off each counter balance. (well pair of crank webs) or is it a case of take of as much as practically possible because any weight off is improvement ? does that make sense?

Crankshaft balance is very important at high RPM. Thus why many manufacturers will use a 4cw crank for motors that are not reving as high. This is to lessen the load on the engine and thus it takes less power to keep it running so you get more power to the wheels. At higher RPM the 8CW crank is heavier but is more balanced for longevity. Ideally the Reciprocating weight of the Rod is balanced out by the counter weights. I always go for the lightest possible parts in the engine. In a 4 cylinder motor, I do not try to keep the amount I take off the crank the same as the rods and pistons. I will get the rods, pistons, piston pins, rings, bearings all done and balanced out. Then weigh the rotating and reciprocating weight. Then get the crankshaft as light as needed and knife edged. Having a heavier crankshaft with lighter rods and pistons will be more balanced and high RPM stability and longevity than a super light, wimpy crank with very strong, heavy, rods and pistons. Getting the crank knife edged and cut down for windage will be more beneficial than a super light crank with poor windage characteristics.

Of course most of this is out of most peoples pockets but if you do a few of the right things here and there, its definitely going to show on the dyno and in smoothness.

-Ted

My first built VE had the full 8cw crank, DET rods, 16VE pistons etc. I wasn't that impressed.

For this build I went back to the 4cw crank, knife edged, std ve rods and again, 16ve pistons. All balanced off course. I know a lot of guys are gonna say it's silly to go 4cw, but with everything being prefectly balanced, I just prefer the weight saving over the longevity issues. I honeslty don't see myself keeping this motor for longer than 40,000km. By then I'm sure I'd have rebuilt again to go 2.2l or even Vet.