time to build a proper engine

[getnpsi]

A bp can spin that high and flow more, but its cool to watch how this goes. A lot of 1.6 guys abandon builds so if you shop you very well might find inbox parts to use and have a budget to make it worthwhile. I'm not clear on all racing classes but if a 1.8 puts you with another division of cars its better to have a maxxed out slow car than something mediocre in the field. I abandoned a twin turbo mustang project because I was building for 500hp daily driven, not outlaw 1000+ a drag racing example.

[TominMO]

You will of course be bringing this new car to Madness VII in 2013? This is assuming the world does not end on Dec. 21 this year.

[Advancedynamix]

A bp can spin that high and flow more, but its cool to watch how this goes. A lot of 1.6 guys abandon builds so if you shop you very well might find inbox parts to use and have a budget to make it worthwhile. I'm not clear on all racing classes but if a 1.8 puts you with another division of cars its better to have a maxxed out slow car than something mediocre in the field. I abandoned a twin turbo mustang project because I was building for 500hp daily driven, not outlaw 1000+ a drag racing example.

Shopping is pretty much done. All the parts in that list are here at my shop. I just need timing tensioner pulleys and a new OEM water pump (I have a new aftermarket one, but don't trust it) to make a complete engine.

I know a BP can make more tq/hp with the same or less effort. I have been building racing engines for about 20 years, many of those engines were for professional road racing teams in several different countries. I currently help build top fuel and nitro funny car engines. This isn't my first rodeo. I have chosen the B6 engine knowing exactly what I need and how to do it. The seldom told truth is that the BP engine is drastically less harmonically stable than it's little brother. I would have to give a year long physics class to explain exactly why. Here is the simple explanation.
Bigger pistons and more stroke have several adverse affects on harmonics. More osculating mass, faster acceleration and deceleration rates of that osculating mass and higher forces applied on power stroke all make for more rapid variation in torque output. This variation is recorded in a frequency. This frequency is roughly 15 percent stronger from a BP than it is from a B6. Rod ratio has a lot to do with this, and the BP engines rod ratio is it's worst enemy. For those who learn better looking at graphs, here is an excellent page compiled by a devoted mazda engine enthusiast that shows what I'm talking about. http://www.miata.net/garage/KnowYourCar/S11_Piston.html

Why is this frequency such a big deal? Because a pulse frequency has a tendency to break, shatter, pound and tear things. That means a BP engine is 15% more likely to break traction, shatter gears and oil pumps, pound diff pins and tear chassis mounting points at the same output level as a B6.

I only need around 180-200 ft lbs of torque (I can easily get that from a B6 with an ideal torque curve for traction). Also, I don't want to reinforce the chassis or drivetrain, so the added strain and weight of a BP are not worth the slight torque advantage in the lower RPM range (which I don't want anyway). For this build, a BP is not ideal. For my future build it will make more sense.

This car is already amazing on the track. I don't want a drastic change, I just need a little more grunt and longer legs. This is not a bragging rights kind of build, in fact I may never post the dyno results, as they won't be impressive and most people will wonder what the point of building the engine was. Fully understanding the point of a well thought out engine usually requires a ride in the car while it's doing what it was built to do. It won't feel fast, it won't seem scary, it will just easily and effortlessly slip by the competition weekend after weekend. HP and TQ numbers don't win races, especially in a series that is judged by HP to weight ratio.

You will of course be bringing this new car to Madness VII in 2013? This is assuming the world does not end on Dec. 21 this year.

I hope the world doesn't end, I have more projects planned. Lol. If Tweak isn't at FM7, you can bet I'll bring something even better. Just have to wait n' see.

[scitzz]

http://www.miata.net/garage/KnowYourCar/S11_Piston.html

Great write up, I wish I understood all of it. Bookmarked, worth studying. I have been thinking BP for the quarter mile. Thoughts on that compared to B6?

It won't feel fast, it won't seem scary, it will just easily and effortlessly slip by the competition weekend after weekend. HP and TQ numbers don't win races, especially in a series that is judged by HP to weight ratio.

Good plan. Seeming scary means it is dangerous, and poorly built.

I hope the world doesn't end, I have more projects planned. Lol. If Tweak isn't at FM7, you can bet I'll bring something even better. Just have to wait n' see.

You mean this build won't be finished in time for FM6? Bugger.

[Aaronbrook37]

Charlie, when was the last time you posted something and I didn't learn something? Definitely subscribed... this thread looks fantastic. Great to have you on-board the forum!

[Advancedynamix]

Great write up, I wish I understood all of it. Bookmarked, worth studying. I have been thinking BP for the quarter mile. Thoughts on that compared to B6?

I think the bp is a better choice for a drag car, or even a street car that gets mostly drag raced. Just like a big block as opposed to a small block v8 (I know about the exceptions to this vague statement, lol). In road racing an engine is exposed to the dangerous harmonic zone for drastically longer periods of time. Also, drag racing tires are better suited to dampen these harmonic frequencies. Last but not least, there are LSD diffs available that are well suited to straight line performance, but nothing really well suited to road racing.

Charlie, when was the last time you posted something and I didn't learn something? Definitely subscribed... this thread looks fantastic. Great to have you on-board the forum!

Thanks Aaron

[kumalaba]

bp cheaper & faster!

[scitzz]

Charlie, when was the last time you posted something and I didn't learn something? Definitely subscribed... this thread looks fantastic. Great to have you on-board the forum!

^^This^^

[Advancedynamix]

[Movin]

:eeeeeek: :eeeeeek: NOooo.....you wouldn't would you??!!

[Advancedynamix]

Well, I got the clutch for it.

[Advancedynamix]

Just kidding. The guys at work think they are funny. They want me to put a blower on my car, but it's not happening (especially not a 14-71, lol).

[FestYboy]

Charlie, i'd be rather dissapointed if you DIDN'T post a dyno graph... i wanna see that torque curve. (i like torque curves.....)

[Advancedynamix]

Charlie, i'd be rather dissapointed if you DIDN'T post a dyno graph... i wanna see that torque curve. (i like torque curves.....)

Okay, but I'm not sure if I'll have the time to put it on the engine dyno (still don't have a destroyed g series bell housing to make my adapter) to get a true SAE net. But I can always put it on the Dyno Dynamix electric brake chassis unit down the street. Here is where the car stands now. Note that the TQ spike is a caused by a boost fluctuation that is common when running such a small internal wastage. It's not as drastic when pulling the car, since the electric brake wasn't calibrated to the weight of my festiva.


I love the way the TQ comes on in this car, but I'm selfish and I don't want my party to end at 5500 rpm, I want at least 2K more range to pull those Porsches in on the straights.

[Uhuzit]

.....to pull those Porsches in on the straights.

Thatīs the spirit! Hehe..