LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently Sun Dec 21, 2014 1:21 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 10 posts ] 
Author Message
PostPosted: Mon Apr 05, 2010 10:04 pm 
Offline

Joined: Wed Oct 08, 2008 12:22 pm
Posts: 168
Location: Austin Texas
Any thoughts about http://www.usa7s.com/vb/showthread.php?t=4844?

This approach means no sequential shifting and greater overall weight, but it turns the engine around, rotates it to a vertical (more vertical?) orientation, and moves it laterally a few inches towards center. Turning the engine around means the layout will be better for left hand drive cars.

Interesting and worth watching, I think.

For some the bike's transmission is a huge reason to use the bike engine. For others maybe an "intermediate" approach with the practicality and engine packaging advantages of a car transmission might make a better, but still really fun, street car.

What remains to be seen is how well executed the project, and apparently following product (no affiliation), will be.

Dean


Top
 Profile  
 
PostPosted: Mon Apr 05, 2010 11:36 pm 
Offline
User avatar

Joined: Thu Nov 20, 2008 10:20 am
Posts: 1025
Location: Subs of Detroit, MI
Creative no doubt, but i can see the time, money, and thought spent better elsewhere. The busa transmission isnt bomb proof... but neither is the Miata

_________________
2007 R1 Powered Mid Engine Street & Track Car
Build Log: viewtopic.php?t=4970
Quote:
On the cool points scale you rank just above Isaac Newton and just under Batman.


Top
 Profile  
 
PostPosted: Tue Apr 06, 2010 12:23 am 
Offline
User avatar

Joined: Tue May 08, 2007 9:50 am
Posts: 601
Location: Minnesota
I think it's a very interesting project. Solves most of the typical BEC "problems" (no reverse, weak clutch, close ratio gearing), but with the engine turning at 1.6X miata RPM for the same MPH it's probably a better racecar than street car. I've pondered arrangements like this before but never thought to tap the transmission input shaft for the drive, that's prettty clever, but it will be interesting to see what they have to do to properly support the (relatively) heavy miata flywheel. It always seems to me that the extra cost of the Busa isn't worth the moderate increase in performace vs a 1000cc bike engine, but I'm sure that will become somewhat irrelevant compared to the cost of all the custom parts necessary.

I've considered a Yamaha snowmobile engine (as have a couple others on this forum) in a similar arrangement . It's basically an R1 bike engine without the transmission and with a dry-sump, it also has a built in primary gear reduction, but only at 1.19:1. Since it usually has a CVT hanging off the side the PTO shaft already has good bearing support and is easily accesible. It wouldn't have all the torque that the Busa has with that 1.6:1 reduction, but I'd also be putting it in a car that weighs ~half what that Miata will weigh.


Top
 Profile  
 
PostPosted: Tue Apr 06, 2010 3:01 am 
Offline

Joined: Wed Oct 08, 2008 12:22 pm
Posts: 168
Location: Austin Texas
Regarding how not-nice it would be on the street with the Hayabusa engine at 1.56 the Miata rpm.

Assuming the same rear end ratio, this is mitigated to a just a 22% (1.56*0.814/1.043) increase over the Miata rpm on the highway since the Hayabusa 6th gear is 1.043 while the Miata's 5th gear is 0.814. A 22% increase in rpm sounds reasonable to me for a higher revving engine.

If the car was for track days only, I think I'd prefer to stick with the bike transmission. For the street, or if it just made a much better package with the engine more upright, on the right, and closer to center, I think they may be on to something. I don't think I'd want the planned set-up in a Miata, but in a car under ~1200 pounds I think it might be worthwhile. I don't know what they'll come up with regarding cost. With the engine more upright I wonder if a dry sump would become unnecessary? Rather than spending money on a dry sump system, maybe these parts with a Miata transmission would cost about the same amount..?

I have a 2007 Hayabusa engine... I also have 5 kids and too many part time jobs at the moment. I wonder if I'll get to my project before they get their design and manufacturing sorted out (at least two years if they follow through, I'm guessing)? One could always take a do it yourself approach to this, but I think I'd only go this route if I could buy nicely designed, high quality (proven reliable enough) parts at a fair price.


Top
 Profile  
 
PostPosted: Tue Apr 06, 2010 10:10 am 
Offline
User avatar

Joined: Tue May 08, 2007 9:50 am
Posts: 601
Location: Minnesota
Their plan is to completely remove the bike transmission and clutch. They will be replacing the inermediate shaft with a custom one that sticks out where the bike clutch was and mounting the miata flywheel to that. Presumably the adapter that mounts the engine to the miata bellhousing will bolt on where the clutch cover was and (I suspect) provide some additional support to the extended shaft.


Top
 Profile  
 
PostPosted: Tue Apr 06, 2010 1:35 pm 
Offline
User avatar

Joined: Wed Apr 15, 2009 4:34 pm
Posts: 123
Now I understand...looks very promising. I like the thought of it; we'll definitely see more ideas similar to this down the road :)


Top
 Profile  
 
PostPosted: Tue Apr 06, 2010 11:15 pm 
Offline
User avatar

Joined: Fri Nov 07, 2008 4:48 am
Posts: 1090
Location: snow city - it's wet!
I does sound very innovative and it may be a decent solution to some of the inherent disadvantages with running a BEC.

My concern is the weight; I went BEC to remove as much weight as reasonable from my car. Since we're usually building very light vehicles, my idealized solution would be alternate gearsets to spread out the usable power over a wider range of gearing. Also loosing the bike transmission would remove the sequential transmission and make building a flatshift solution more difficult.

I guess the real test will be how much total weight is added by dropping out the bike gearsets and then adding back all the automotive stuff. On the plus side this could potentially open up bolting a bike engine directly to a variety of longitudinal (Subie, Porsche, etc.) and transverse transmissions.

_________________
.. in the world


Top
 Profile  
 
PostPosted: Sun Apr 11, 2010 10:28 pm 
Offline

Joined: Sat Feb 09, 2008 1:05 am
Posts: 678
Location: San Antonio
It'll be interesting to see how this pans out.

_________________
JSullivan


Top
 Profile  
 
PostPosted: Wed Nov 23, 2011 4:52 am 
Offline
User avatar

Joined: Wed Apr 01, 2009 7:03 pm
Posts: 35
Location: San Antonio, Tx
JSullivan wrote:
It'll be interesting to see how this pans out.



Well now you can see how it pans out. This link will take you to chapter 3,4,5.... the 1st link above gets you chapters 1&2.

http://www.motoiq.com/projects/project_ ... 419/2.aspx


RCD

_________________
Not only is my glass have empty it has a crack in it and leaks.

94% of Americans say "OH SH=T!" as they dive into a foxhole the other 6% are from Texas and say "Here HOLD my beer and watch th

"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."
Benjamin Franklin, 1759


Top
 Profile  
 
PostPosted: Wed Nov 23, 2011 8:15 pm 
Offline

Joined: Fri Jul 17, 2009 10:56 pm
Posts: 378
Yeah I don't get the point,read a bunch of that eons ago and the amount of effort/$$ involved just doesn't seem to solve many issues.The single biggest reason to go BEC is the lightweight and compact easy all in one pkg,this kinda screws both of those.

A quaife reverse is pricey but no where near as that sucker is going to be and takes up far less room and weighs less,just pointing out something I think they've missed. :)


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 10 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY