Quote:Yes, it was commonly done. But the 327 was still faster. Only if you are limited to class rules (e.g. Trans Am 5-liter class) did this actually work out better. Btw, the stock Chevy 302s didn't even rev to 6,000 rpm ... but that's another story.

I don't know anything about the stock 302's, but I have seen many capable of 10,000 rpm built by hot rodders. One of the mechanics that works for me has a 302 in his Vega that turns 10k no problem, but you are correct, it's far from stock. In any case, a destroked crank allows for higher rpm.

An A12A crank will fit in an A14 block. Just over 1200cc's is the displacement. Longer than stock rods are used, an engine with a bit more torque is the result. An A12A is the base engine in a north American '79-'82 Datsun 210. (B310 model code). I think it's a Stanza in AUS & NZ.
The Datsun 1200 I pit crewed for last year had an engine like this. It put out over 180bhp. This is a fairly common setup in SCCA GT5 racing in the US.

PDS
The reference to the max legal boost pressure was found in Australian Street Rodder Magazine, April 2004.
It's in the article "National Guidelines for the Construction & Modification of Street Rods in Australia"
Section 1, Engines, reads in part "The use of turbocharged or supercharged engines may require engineer approval. The maximum boost for turbocharged or superchatged engines is 9psi [63kPa]"

If it isn't law yet, it looks like it soon will be.

DaveB
The use of the 1200 crank in an A14/15 block, with A14/15 rods will certainly reduce the compression, particularly if A15 pistons are used as the piston crown will fall short of the deck by a full 6.5mm If that isn't low enough, i dont know what would be.

Engine capacity would be somewhere near 1290cc [i'm too tired to work it out] I was interested in your comment about "a bit more torque being the result."
A bit more than what?

The 7mm reduction in stroke would yeild less torque than the full length 77mm stroke of the A14. The new stroke is 13mm less than the A15, thats a half inch less, so i suggest that, all things being otherwise identical, the short stroke engine would have LESS torque than either of the other two examples.

With really low compression, one should be able to use high boost, but off-boost, a 6 to 1 [or less] compression engine would be a slug, & this is the dilema of the street driven blown engine, & this is where positive displacement blowers have an edge over turbo's.

Well there you go, I just read Dattodudes thread and I realise it only for rods, but it's gonna be good to see how they actually regulate this. I mean is it gonna be a requirement that at rego time the rod has to be dynoed.

Back on the subject of low comp, I do / did know of a bloke running an FJ20 turbo 1600 drag car with stupidly low comp, so low that for it to even idle it needed a hit of nitrous.
Havent heard anything about this car for a while, last I heard he was having trouble with battery voltage dropping halfway down the quarter mile track.
Do any other members know of this 1600? I forget his name but he does efi tuning for Old Man Emu and various other places.
It would be good to hear whats happening with this car.

Cheers Steve

If anyone seriously thinks that the rego nazis will limit a blown big block Chev to 9lb boost, just because it is in a pre 1949 car, but happily allow unlimited boost in the same engine when it is fitted to a post '48 car, i would suggest that you ask yourself if you really think that they are actually that stupid.

Even if they did make that mistake, they would be made aware of it on the day the legislation was enacted, with a demand that the law be applied equally to all.

As for how they plan to measure & enforce the act? Beats me.

Quote:A bit more than an A12. Both engines being close to 1200cc, but one using longer stroke/smaller bore will have "a bit more" torque than the shorter stroke/wider bore, all else being equal (compression, etc) ... according to conventional wisdom. Also, the few extra CCs don't hurt, even though it is minor.

But the long stroke/small bore has these disadvantages for high-rpm use:
- more side-load friction of the piston (one of the biggest friction sources)
- smaller bore often means worse valve breathing, esp. if large valves get close to the cylinder bore

So if you are on a fast speedway road-racing oval, or a Bonneville style top-speed run, you would probably design your engine for high-rpm efficiency.

For a street engine that spends some if not all of its time running at 2000-3000rpm, you might want to build the engine to emphasize low-speed power (aka "torque", but remember, torque actually is made at all speeds).

Nissan seems to have made the stock A12 to work best in the 3,000-5,000 rpm power band, surprisingly high for an econobox, and then throttled it down with small carb, small ports & valves and small exhaust. Result: good economy and smooth throttle response when driven "normall", yet spirited performance if revved up a bit before shifting. The stock 3.90 gears keep the engine right at the beginning of the fat part of the power band at 60mph (100kph).

The first rule of thumb for a fast race car is: use the largest displacement allowed (see b310gx's comment here that "they now have a 1500 cc car limit,so they use a15's"). For a street car, this guidline is often tempered by availability (if you can find an A14, but not an A15, doh! use what you have or can get), cost (if an A15 costs more, you might choose something less expensive) and reliability (but A14 and A15 reliability is about the same). 1607 and bigger stroker motors generally cost too much for the average joe, but some racers use them if allowed, don't they?

Once your engine size is chosen, then things like stoke, bore (and rod/stroke ratio) can be fine tuned if your budget and interests allow.

When I mentioned the a14 block with an a12a crank having a bit more torque, I should have said.' More torque than an a12 or a12a engine.' I should have also said that the a12a displacement @ slightly over 1200cc's is unchanged in the new block if the bore remains the same. An a14 will obviously have more torque overall. The engine I was talking about has longer custom rods, with race pistons & over 13.5:1 comp ratio. With alike cranks, a taller block with longer rods keeps the rod more verticle during the power stroke. This is said to help torque fiqures slightly.

Quote:

the NHRA and the RTA have been working very close with each other on this legislation.

i believe the act you are referring to is to do with reproduction chassis and bodies and pretty much anything with a 'glass body. what they're trying to encourage is original bodies on newer and better designed repro chassis.

the maximum engine size for a "hot rod" is 460ci under the new rules, which includes a turbocharged engine with a max limit of 9psi on a 351ci engine. any more than 9psi and you have to reduce the engine size accordingly, but this sliding scale isn't available yet.

note the ford ci sizes there, their equivelant chevy engines are smaller (454 and 350) but the same rule applies.

you could always declare a 351ci engine with 9psi, and then turn it up for the track, but 9psi is the limit for street use.

so, 20psi on your A14 is perfectly acceptable.

sliding scale, remember.