Fatman0203

Whats the turn around time??

bigmack000

iam pretty sure david can go take the car and get it dynoed to show werhe it makes the power and how much.

side note: no package yet david
joel

3RotorRocket

Holy **** Siiiiick

jimlab

Frictional losses increase as power increases, otherwise drivetrain losses would be a fixed value regardless of power level instead of a percentage which approximates the delta. For that reason alone, a 20B would not make precisely 50% more power than a 13B, even if the turbos, ports, intercooler, intake, and exhaust were identical and exactly 50% more air and fuel were added.

Of course an engine that can burn more air and fuel is going to make more power. No one's debating that. However, the difference in power cannot be solely determined based on the difference in displacement because there are far too many other variables to consider. Bottom line, power potential and displacement do not share a linear relationship, at least not without making a significant number changes which negate a fair comparison with the original configuration.

jimlab

Obviously, and independent results are what I'm interested in, not what "Cam says" or what someone else thinks a 20B will make at X psi. I'd also like to know what the car weighs when finished and what the distribution is.

RotorMotor

iTrader: (5)

one wheel is the same size, and one is slightly larger. pettit makes the twins non-sequential and increases exhaust flow by removing the seq. flapper doors etc (if i remember correctly), and smooths out the bends for better flow. they also jet coat, or ceramic coat the hot sides. other than that i dont think pettit does much to the turbos. BNR can upgrade the 20b turbos for around $2K, (i think they might be able to slap some new cartriges on there... ball bearings would help things alot) but there is only so much you can do with 2 turbos and 3 exhaust pulses. at $2K for the BNR conversion you might as well consider a large single (or even 3 small singles independently run from each exhaust port.... although 3 separate turbos will be kinda heavy). personally im debating between having BNR do my twins, or possibly using 3 singles. one large single is the simplest but im always worrying about lag. the 20b turbo situation can get pretty complicated if you venture too far out there so im leaning toward the twins. -heath

RotorMotor

iTrader: (5)

jim, ill let you in on a little secret that im sure you already know... your car will be better balanced than any 20b powered FD. these motors are PIGS (i should know, ive been rolling one around in the garage on an engine stand for the last week). from what ive read your v8 will be lighter... but then again i chose the 20b on no other basis than the fact that it had rotors.

jimlab

I know, I owned one myself once upon a time.

RotorMotor

iTrader: (5)

OH MY GOD!!! my jaw just dropped open.... im still in shock... jimlab with a 20b next to his car!!!!!! now ive seen it all

jimlab

I know. And that's a stock MKIV Supra cat-back hanging on the wall behind it!

rx7tt95

Cam exaggerates his claims plain and simple. He's a salesman. But he's also a first rate craftsman when it comes to his three rotor setups. No, I wouldn't do them exactly the same way (as if I'm qualified!) but he has great attention to detail and you get a car that actually works well. It's not just thrown together. Just don't expect huge hp numbers out of his setup. His ports are very, very mild for the most part. But the reworked Hitachi's (upgraded compressor wheels) make the car very driveable. Even if you're "only" making slightly above 400rwhp at 13psi, there's lots more torque and flexibility on hand over a two rotor setup. It'll be a fun car to drive regardless. I'm sure you will enjoy it!

I'd be most interested in long term updates with the car and how it functions over that time in a real world basis down here in the steamy heat of Florida's brutal summers.

David Hayes

iTrader: (6)

Thanks everyone for the opinions and thoughts. You are all correct. The bottom line will be determined at the dyno and I'm more than happy to post the results for you.

RX7tt95 is also correct that Cam is a first rate craftsman and has a high attention to detail. Cam first and foremost is concerned with reliability and drivability. Horesepower comes second. I know this all to well from many discussions with Cam and having him fix the crappy work that was done on my car here in Jacksonville.

I went to Cam, although he is pricey, for these reasons and am confident that I'll get good results. I also will post long-term updates (yes, Florida is brutally hot in the summer).

FYI - just place an order for Forgeline WC3s 18X9 (front) and 18X12.5 (back). I haven't heard back from RO_JA as to if they can custom make a set of Formula 5 serises wheels for the back. So, although I love the wheels, I'm taking them off and replacing them. Guess I'll sell them on the forum or ebay them.

paw140

Now you're just being ****. I'm sure Stephen was *estimating* when he threw out the 50% increase in power. But when it all comes down to it, 50% more air + 50% more fuel should more-or-less equal 50% more power. I'm talking about flywheel power, not rwhp.

MichaelFregoe

iTrader: (1)

How long will your car be at Pettit for the conversion?

jimlab

No, I'm being accurate. Stephen pulled 50% out of the air without considering that it's not as simple as multiplying power by the same ratio as the increase in displacement. It doesn't work that way because there are far too many other factors involved.

A 350 CID Corvette LT1 makes 300 horsepower NA on pump gas. My 396 CID LT1 only has 13% more displacement, but makes 100%+ more horsepower, also NA, also on pump gas. Is the difference in power based solely on displacement, or is it based on significant changes to the configuration and rpm range? You absolutely CANNOT base power estimates solely on the difference in displacement. How many times do I have to repeat this before it sinks in??

Significant changes in configuration would be required to make a 20B produce 50% more horsepower than a 13B-REW, any of which negate the original comparison unless they're applied to the 13B-REW also. You can't just stack the deck to skew the results until they meet your approval. How would comparing a modified 20B to a stock 13B-REW be even remotely fair?

Of COURSE you can make 50% more power than a 13B-REW after upgrading everything on the 20B, but the difference in power is no longer based on the difference in displacement, it's based on all the modifications you made. With identical configurations, a 20B will NOT make 50% more horsepower than the 13B just because it has 50% more displacement. Period. End of discussion.

These are the ONLY assumptions you can make based solely on an increase in displacement...
1. The bigger engine will have greater power potential overall
2. The bigger engine won't have to work as hard to produce the same power level, providing a greater margin of safety
3. The bigger engine will have increased low end power because it can consume more air at lower rpm

So are you saying that you don't think frictional losses apply to the engine itself?

David Hayes

iTrader: (6)

Wow, didn't really mean to spark the conversation on this thread. It's pretty interesting though.

As for how long the car will be at Pettit, I'm told 90 days or so.

yzf-r1

iTrader: (1)

it's pretty easy to "spark" good ol Jim into a debate

jimlab

Look who's talking.

That will be an interesting factor as well. "Or so" could mean "x2" or more. Stephen, would you care to speculate on what the time factor multiple would be for a 50% increase in displacement?

HDP

iTrader: (2)

4. The bigger engine will weight more.
5. The bigger engine will be more difficult to squeeze into an already tight engine compartment.
6. The bigger engine will more than likely cost more.
7. The bigger engine will give you true bragging rights... "mine is bigger than yours".
8. The bigger engine will cause debate after debate on what the true advantage of actually having a bigger engine.

Ok, I'm done now

jimlab

Generally speaking, but there are ways to increase displacement without increasing package size or substantially increasing weight. In fact, my 396 is about 35 lbs. lighter than the stock 350 LT1 I mentioned earlier and it's 1/2" shorter in height. A Motown 454 would weigh only a few pounds over the stock 350, but have a 30% displacement advantage. That just goes to show that you can't make assumptions about package size or weight based solely on displacement either.

Unfortunately, you can't bore and stroke a rotary, so an increase in displacement is absolutely accompanied by an increase in weight and package size. The Motown 454, on the other hand, is no bigger physically than a mundane 305.

This is based on physical size, not necessarily displacement. See above.

Any time you have to use "more than likely" to qualify something, you've already got a hole in your statement.

A 350 CID SBC is infinitely cheaper than a 120 CID 20B, and you could easily surpass the 20B in horsepower for less money. Aftermarket plays a big role in how expensive a given platform is to modify and maintain.

There's always someone bigger. Shafiroff Racing now builds a 472 CID small block based on a Dart II casting.

Drivability. Increasing displacement broadens the power band, improving low end power and reducing the tendency to have a very peaky power band.

Power potential. A 454 with 10 pounds of boost ownz jo0!!1!

pugg57

just to be a complete ***... not that i would considder it... but would it be possibel to drop in a Ford like 2.5-3.0L V6 with a turbo for each bank?

yzf-r1

iTrader: (1)

Drivability. Increasing displacement broadens the power band, improving low end power and reducing the tendency to have a very peaky power band

this is the key issue....ask any roadracer

and it's why Porsche's kick FD butt at the track, even if the peak hp is the same or maybe even a little better with a "bad ***" T-78 or whatever

it's also why these dyno queen Supras with 180 hp below 3800 rpm absolutely suck at the track

SPOautos

Actually, I didn't say exactly 50%, I said ABOUT 50%, sure there are some losses here and there but they are minimal.

IF EVERYTHING is equal and you put the same amout of air and fuel in each chamber of the 13b then the same out of air and fuel in each chamber of the 20B your going to be combusting 50% more air and fuel and its going to make about 50% more power minus some small amout of increased ratio of frictional losses. The set up and tuning of a stock 13b and a stock 20B arent the same so thats not a good comparison. I still think if you run the same duty cycle on your injectors in every case every chamber is getting the same fuel and air you are going to make approx 50% more power since your consuming 50% more fuel and air.

You come up with a good reason as to why consuming 50% more air and fuel doesnt create about 50% more power and I'll listen. Matter of fact I would like to listen....I'm always ready to learn

BTW - I'd imagine if you kept EVERYTHING the same on your LT1 and left it all stock and just stroked it out it would prob only increase power around 13%. Your new engine is running higher compression, better VE with better heads, better exhaust, better manifolds, better cam selection ect ect ect. If you kept the VE and tuning (a/f ratio) the same in both applications and just increases size I bet it would be very close to 13% increase.

STEPHEN

paw140

Sure, there is more involved. I'm talking about *estimating*. I'm not saying that adding 50% displacement is going to increase power by 50.000%. My point is that, all other things being equal, 50% more fuel + 50% oxygen = 50% more engery. Combusting 10 g of fuel makes twice as much heat energy as combusting 5 g of fuel. It's as simple as that. Again, I'm talking about estimating based on reasonable assumptions and knowledge of how internal combustion engines function.
Now you're comparing apples to oranges. Why are you bringing this up? Your 396 is so worked over and ingests so much more air than a stock 350 that of course it's going to make more than 13% more power.
I NEVER said this, nor implied it. You are right.
We're not talking about comparing a stock 13BREW to a stock 20B. We're talking about comparing a 13BREW to a 13BREW with essentially another rotor added, with identical porting, and corresponding exhaust, intake, and turbo mods to make up for the difference so that it flows as well as a stock 13BREW.
Maybe not, but it should be pretty damn close.
Huh? Of course there is friction in the engine. Adding a 3rd rotor will increase the overall friction in the engine, but the friction per rotor will be roughly the same.

paw140