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When is Power Output...Enough?

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slightly modified Avatar
slightly modified Silver Member Chuck Royer
Hayward, CA, USA   USA
1964 MG MGB "SLIGHTLY MODIFIED"
Mr. Stabes MGB is a unique and wonderful car. My "B" was built around a SBC, have tried to remain somewhat stock looking. I do not expect anyone to ever drive mine except ME! I thought I would end up with around 400 HP, got a deal on my engine that I couldn't refuse, it ran 128 MPH in the 1/4 mile@3800lbs in full race tune (math says that took 640hp), have detuned it in my "B",most locals around here think it still makes a least 500hp (racers, engine builders, people who have ridden in it), I honestly do not know, does seem pretty sporty though.--------------------------------------Chuck

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Mustangsix Avatar
Mustangsix Gold Member Jack Collins
Orlando, FL, USA   USA
I believe that the correct recipe for determining how much power you need is to increase power until you need a change of underwear. Then decrease by 5 hp.....


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NOHOME P P
O, ON, Canada   CAN
1967 MG MGB GT "Maggie (GT From Hell)"
How much power your engine can deliver as a peak number is irrelevant. Recall that you have a pedal that dispenses said power on demand? So in theory, no amount is "Too much"

More important is how the power is delivered. A lot of power obtained via tall lobes and a lot of overlap is not much fun on the street, and yet it will only be delivering low power in the operating range we drive around at. If your pedal was connected to 1000 hp of linear power, I suspect most would stop asking the pedal for more at about the 300 hp point.

Pete

Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd, Florence, KY, USA   USA
Do you want HP or do you want Torque? Sort of depends on what you use the car for. Probably HP for the dragstrip, torque for the street. I'm almost never found at a dragstrip.

Jim

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bills Avatar
bills Bill Spohn
W. Vancouver, , BC, Canada   CAN
In reply to # 3736591 by NOHOME
More important is how the power is delivered. A lot of power obtained via tall lobes and a lot of overlap is not much fun on the street, and yet it will only be delivering low power in the operating range we drive around at. If your pedal was connected to 1000 hp of linear power, I suspect most would stop asking the pedal for more at about the 300 hp point.

Pete

And it is a whole different thing if you have an NA car (tends to be peaky when highly tuned) or a blown car, which tends to have a more linear presentation of power. easier to get into trouble with the right pedal with the latter, although most manufacturers program the engine not to deliver full torque from the ground up in order to take it easy on the drive line.

Example (LNF). The torque 'curve' is programmed, not natural. The curves for the tuned engine still have limitations but are a more natural arc. The delivered torque is actually limited below 2000 rpm as it would deliver like a V8 otherwise (some of the old big block Mopars I used to fool around with approached 500 Tq by 3,000 rpm.)





Bill Spohn www.rhodo.citymax.com/carstuff.html
Current: 1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1957 Jamaican MGA (200 bhp)1965 1971 Jensen Interceptor (350 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
2007 BMW Z4M coupe (340 bhp)
Recent: 1969 MGC roadster (175 bhp),Jensen CV8 (375 bhp),
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
North Vancouver BC




Edited 1 time(s). Last edit at 2018-05-15 10:10 AM by bills.

Jim Stabe Avatar
San Diego, CA, USA   USA
In reply to # 3736598 by Jim Blackwood Do you want HP or do you want Torque? Sort of depends on what you use the car for. Probably HP for the dragstrip, torque for the street. I'm almost never found at a dragstrip.

Jim

I agree, torque is a lot more fun. Mine makes more torque than HP and the good news it makes down low - over 200 ft lbs at 2000 rom, over 300 ft lbs at 2500 rpm and over 400 ft lbs at 3000 rpm.. That's what really sets you back in the seat



Jim

"If you want me to agree with you then we would both be wrong"

'66 MGB widened 11" with supercharged LT1 Chevy and 6 speed, C4 Corvette suspension
Pictures here Part 1 http://forum.britishv8.org/read.php?13,7581
Continued in Part 2 http://forum.britishv8.org/read.php?13,22422
Continued in Part 3 http://forum.britishv8.org/read.php?13,33108
Continued in Part 4 http://forum.britishv8.org/read.php?13,40751
Continued in Part 5 http://forum.britishv8.org/read.php?13,48698,48698#msg-48698
Continued in Part 6 http://forum.britishv8.org/read.php?13,61672



Edited 1 time(s). Last edit at 2018-05-15 05:05 PM by Jim Stabe.

scott68B Avatar
scott68B Scott Costanzo
Central, OH, USA   USA
1968 MG MGB "GM 5.3 LS4 V8"
My LS4 also makes more torque than HP. I have 300 ft/lbs or more from about 1800 rpm to 5200 rpm. Peak is 323 at 4400 rpm. Not a lot by LS standards but it moves my B along pretty well.

Jim Stabe Avatar
San Diego, CA, USA   USA
In reply to # 3736632 by scott68B My LS4 also makes more torque than HP. I have 300 ft/lbs or more from about 1800 rpm to 5200 rpm. Peak is 323 at 4400 rpm. Not a lot by LS standards but it moves my B along pretty well.

The LS engines have ridiculously flat torque curves, can't beat them for a street car.



Jim

"If you want me to agree with you then we would both be wrong"

'66 MGB widened 11" with supercharged LT1 Chevy and 6 speed, C4 Corvette suspension
Pictures here Part 1 http://forum.britishv8.org/read.php?13,7581
Continued in Part 2 http://forum.britishv8.org/read.php?13,22422
Continued in Part 3 http://forum.britishv8.org/read.php?13,33108
Continued in Part 4 http://forum.britishv8.org/read.php?13,40751
Continued in Part 5 http://forum.britishv8.org/read.php?13,48698,48698#msg-48698
Continued in Part 6 http://forum.britishv8.org/read.php?13,61672

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GWHITE75 Avatar
GWHITE75 Gold Member Gary White
Sugar Land, TX, USA   USA
1973 MG MGB "OldBlue#2"
1975 Chevrolet Corvette Stingray "Old Red"
2006 Chevrolet Corvette "OldBlue"
In reply to # 3736598 by Jim Blackwood Do you want HP or do you want Torque? Sort of depends on what you use the car for. Probably HP for the dragstrip, torque for the street. I'm almost never found at a dragstrip.

Jim

And the reason I haven’t ruled out the 4.3l Chevy, flat torque curve to about 300lb/ft. I am not too concerned about how high the engine revs more than driving around slowly and not having to shift as much.

V8MGBV8 Avatar
V8MGBV8 Carl Floyd
Kinggsport, TN, USA   USA
In reply to # 3736616 by Jim Stabe
In reply to # 3736598 by Jim Blackwood Do you want HP or do you want Torque? Sort of depends on what you use the car for. Probably HP for the dragstrip, torque for the street. I'm almost never found at a dragstrip.

Jim

I agree, torque is a lot more fun. Mine makes more torque than HP and the good news it makes down low - over 200 ft lbs at 2500 rom, over 300 ft lbs at 2500 rpm and over 400 ft lbs at 3000 rpm.. That's what really sets you back in the seat

Of course, your tires & Corvette suspension can more easily handle that torque. Most MGB conversions with leaf springs & 205 tires can't.

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slightly modified Avatar
slightly modified Silver Member Chuck Royer
Hayward, CA, USA   USA
1964 MG MGB "SLIGHTLY MODIFIED"
I agree with the above statements, it just happens that I have a high RPM , very peaky SBC, its low RPM, low torque characteristics actually make it pretty easy to drive (probably still making 250-300lbs. of torque at 3000rpms), I know my engine is not the most practical choice (not practical at all), the sound (beastly) and the smooth rush of power at moderate throttle openings is totally addictive. If I had it in a 3500lbs. car it would be undriveable on the street, in my "B" it works for me. Heck just warming it up, the whole car throbbing with anticipation gives me goose bumps.-------------------------------Chuck

Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd, Florence, KY, USA   USA
Yeah, I think I'm in the same ballpark with you guys on my 340 Buick. Haven't dyno'd it and won't for awhile. Pretty easy to break loose those 315's but they are 10 years old. Just looked at my cam card, .436" lift @ .212 duration (.050) and it's pretty streetable. I don't really think it's taking anything away down low. 10.6 CR and 5 psi boost does help. Need to shim up the valve springs a bit but no hurry. It'd probably be a bit much on 205's but it really depends on how you drove it. Does have the potential to "make yer eyes wide" as an old buddy is fond of saying.

Jim

scotabbott Avatar
scotabbott Scot Abbott
Pittsburgh, Pa 15216, USA   USA
1974 MG MGB "Bee"
A couple of ideas come to mind about when is enough power enough.

scotabbott Avatar
scotabbott Scot Abbott
Pittsburgh, Pa 15216, USA   USA
1974 MG MGB "Bee"
A couple of ideas come to mind about when is enough power enough.
First: For street use,
: (1) Stock RBB is underpowered
(2) Anything more than 1 hp/10# is overpowered.
(3) Those statements put the GM V6 and Rover V8's in the sweet spot.

Cars set up like that are plenty peppy but are not so tempting to make us act like teenagers (again).

slightly modified Avatar
slightly modified Silver Member Chuck Royer
Hayward, CA, USA   USA
1964 MG MGB "SLIGHTLY MODIFIED"
Scot, I'm guessing that my "B" having less then 5lbs. per horsepower might be slightly overpowered, it sure is fun though.---------------------Chuck

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