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Reasonable power out of a good street B motor?

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Christopher H

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How much power can be made in a streetable MGB with reasnable modifications? Can these cars be made as quick as a Miata?

Yes, I don't know much about MGB's but I'm intersted in learning.

Chris
 
It would depend on which year Miata. The early Miata's had about 115 horsepower. A B with minimal mods could hit that number using a hotter cam, hotter coil, free flow exhaust and either very well tuned SU carbs or Weber downdraft. It would still be very "streetable". The original B had 94hp (I think) so getting to 115 is an increase of about 20%.
The new Miatas have horsepower around 140 and to get a B that end would be extreme modifications and for a variety of reasons would only be for racing (I think).

John
 
The rubber bumper cars must be off by a good bit then because grassroots motorsports was only getting about 65-70 as I recall out of a modified R/B car. 95-100 is fine...

Thanks for the info, guys.

Chris
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I read in Grassroots motorsports that there's some guy in San Jose, CA who claims he can get 165 HP out of a B with cams and headers.

I'm skeptical though
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with the modifications including, a 1/4 or 1/2 race cam (either piper or kent), hd valve springs and caps, piper roller rockers, peco or ansa headers, free flow exhaust, alum cross flow head, weber 45 dcoe sidedraft carbs, k & n or longflo air filters, 45d distributor (recurved for centrifical advance), 40,000 volt coil, about 130-140hp is realistic.
the 1/4 race cam is streetable, with acceptable idle. the 1/2 race cam will give you a somewhat rough idle.
it all boils down to "how much do you want to spend"??

[ 01-10-2003: Message edited by: XJRpilot ]</p>
 
Are you trying to match horsepower numbers, or actually make the car go as fast as a Miata? If I remember correctly, the MGB is a bit lighter than a Miata (chrome bumpered, that is), and is a bit easier to get lighter bits for without gutting the interior, etc. It's a bit harder to lighten up the Miata without stripping it bare.
-Wm.
 
I've owned a Miata, I've not owned an MGB. I am very interested in buying an MGB at some point. I've just ridden in some rubber bumper B's that were amazingly slow. I'm trying to make sure that I can make the car a somewhat fun street driver. Fair enough?

Also, I have an interest in possibly autocrossing a "B". I've done the SCCA flagging thing and I'd like to race. I've found drag racing somehat boring and I don't have the cash to race wheel to wheel at some place like Mid Ohio or Road America.

I think the B would make a good autocross car because of it's small size...in other words with a little less width and length I think I'd be less likely to hit cones than say if I raced a Camaro.

Chris
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BTW, thanks to everyone for your help.
 
Just for base lines:

Grassroots quoted a stock RB MBG w/ single carb as 50 HP to rear wheels. With 2 carbs, KN filters, header and fancy distrib (but no internal mods)they got up to 64 at rear wheels on same car.

I've seen stock RB MGBs run autocross...they're *still* fun....that's what it's all about, right?
 
Rubber bumpered Bs are deathly slow, if left stock, because of the loads of emissions stuff that was bolted on to the engines that sapped horsepower. earlier ones are definitely quicker, but not nearly as fast as a stock Miata. I have a stock (except for a Borla exhaust) '96 Miata, and my father has a mildly uprated '71 MGB. The Mazda is definetly faster than the B, but the MG does not really have any problem keeping up with traffic, and will cruise at 80 without much fuss. The MG engine does not rev nearly as high or as quickly as the Miata, but this is offset by a nice slug of torque right at the bottom of the rev range-to get a similar push in the back from my Mazda, I have to go up to around 5K on the tach. The B starts at like 2K.
Here's the caveat-we have no idea what performance mods were done to the B prior to Dad buying it. The previous owner had installed an uprated cam, and free-er breathing air filters, supposedly bored it out a touch, and the air pump is MIA. Our local old car gurus can't figure out which cam is in there (without a teardown, I presume), but have managed to get timing and carburetion adjusted to suit the cam. It gives a somewhat lumpy idle, but nothing extreme. Gets great gas mileage too. Like I said, not as quick in out and out terms as the Mazda, but no slouch in its own right. Handling is great, very neutral, so I think a B would make a fine beginners autocross car.
-William
 
As I recall, different countries used different size horses. I don't know if that is still true; but the Japanese used something called JIN, United States expressed it as SAE/BHP and the Germans as DIN. It was for advertizing purposes, Does anyone know if horse power has been standardized? A 140 JIN HP Miata maybe comparable to 130 SAE/HP in a MG.
 
Since we are on the subject,

What can I get out of my MGC Engines ??

I'm planning on having my local machine shop punch out the bores, but who make good preformance parts for my C ??

Hey ChrisH, I'm near Columbus (New Albany). Do you know Eric Jones (in Delaware, going up to Mid Ohio) (I have two C's (GT and Roadster), but have to finish my Chevy II then comes the C's)
 
Simple answer to your question is

HOW MUCH MONEY ARE YOU WILLING TO SPEND?
 
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