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ClayW

Engine Questions

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The motor that I have in my garage is about to return to a working, non wrecked car. My brother the mechanic rebuilt it for me and I put about 10K miles on it before I wrecked my 1600 and it went into storage.

I currently own a 1970 2002 that is about to receive this motor (the car's PO forgot to mention a plethora of shitty workmanship and missing parts, so I don't trust the "rebuilt" motor that burns a quart of oil every 600 miles). The motor that I'm installing has 9.5:1 piano top pistons, port-matched but not polished intakes and exhaust ports, a Weber 32/36 DFAV, Pertronix electronic ignition, an E12 head, a $20 long tube header and will get one of Ireland's crank scraper/windage tray things. I'm not sure about the cam, so I'll assume it's stock.

So, what's it got? I have no idea what the horsepower is, but I got as high as 30 mpg on the highway with an overdrive 5 spd and a 4.11 out back.

Also, I'm planning on adding EFI (a la Steve @ Finkbuilt.com and Zenon @ zeebuck.com) along with the distributorless ignition. What do you think that will give me?

I'm at the decision-making stage here, so any advice is welcome. Should I look at a Schrick 292 cam? I like the extra power, but I'm not taking the car to the track. I wonder if I can get 35+ mpg without letting Escorts beat me.....

Thanks in advance!

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A combination like that should be a nice running version of a stock engine. In other words, it might make 5 or 10 hp more than stock, no more, and it should be able to get good gas mileage if you drive it gently. The stock cam will like the slightly increased compression ratio, and will make for the good mileage. The small carb likewise, if you keep your foot out of it it will mostly run on the primary venturi.

Adding the EFI and the distributorless ignition will only give you a gain if what you have is poorly tuned. Unless you change the air-pump somehow, the basic characteristic of the engine won't change, it will just do what it can a tad better. It should run a lot better in terms of driveability, though. The stock cam is governing the ability of the engine to pump air and will really decide the character of the engine a lot more than external parts that you add on.

If you go to a 292 cam you'll lose bottom end and gain top end and lose a lot of economy. That means you have to drive it harder to get back to where you were at, and harder still to reap the benefit of the longer cam. At 9.5:1, you have a reasonable CR for that cam on the street. Your weak link will be the small carb. I really think that the 32/36 carb is good for engines up to 90 - 100 hp only, at a stretch. I replaced twin SU's with a 32/36 on my MGB, probably lost 10 - 15 HP. But gained a ton in being able to actually drive the thing reliably...

Brian

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....assuming I go EFI with a nice, big 58mm throttle body (E30 325is), should I still think about a cam swap? I really don't want to lose any fuel economy. What cam should I look at, if any?

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The motor that I have in my garage is about to return to a working, non wrecked car. My brother the mechanic rebuilt it for me and I put about 10K miles on it before I wrecked my 1600 and it went into storage.

I currently own a 1970 2002 that is about to receive this motor (the car's PO forgot to mention a plethora of shitty workmanship and missing parts, so I don't trust the "rebuilt" motor that burns a quart of oil every 600 miles). The motor that I'm installing has 9.5:1 piano top pistons, port-matched but not polished intakes and exhaust ports, a Weber 32/36 DFAV, Pertronix electronic ignition, an E12 head, a $20 long tube header and will get one of Ireland's crank scraper/windage tray things. I'm not sure about the cam, so I'll assume it's stock.

So, what's it got? I have no idea what the horsepower is, but I got as high as 30 mpg on the highway with an overdrive 5 spd and a 4.11 out back.

Also, I'm planning on adding EFI (a la Steve @ Finkbuilt.com and Zenon @ zeebuck.com) along with the distributorless ignition. What do you think that will give me?

I'm at the decision-making stage here, so any advice is welcome. Should I look at a Schrick 292 cam? I like the extra power, but I'm not taking the car to the track. I wonder if I can get 35+ mpg without letting Escorts beat me.....

Thanks in advance!

Isn't that the question - I got into it with just about everyone on the FAQ in my early posts over this... how do I get 200hp and 35mpg?? anwer is easy, cheap and readily available - Get a Honda!

Seriously I'm in the same boat you are. I'm building two motors and one I want as a tuned down nice DD motor. It's stroker and I ordered 9.5:1 CR pistons and i'll run a 292 cam or maybe try and get a re-grind OE cam that's somewhere between stock and 292. I'm gonna run stock valves but port and polish, run either (haven't decided yet) an E30 318i EFI intake or an early E21 'log style' EFI intake. you have to remember two things - there is no replacement for displacement and as someone's sig. reads: speed costs $ - how fast do u want to go?

Start off not by thinking about what you want numbers wise but by realisticly deciding on the purpose of the vehicle/motor. Will you ever race it? Will u ever autox it? many autox stock cars and do well - mor the driver than the motor.

My old, tired, stock M10 with 32/36, 3.45rear end and 5-speed OD gets ~28 mpg combined regardless of what people believe. The speedo is calibrated and the nubmers don't lie. With that said I can push it and get 14mpg or I can really feather it on the highway and get 33mpg. If you are building a DD car do things that will increase low end torque - or avoid things that take away low end torque. I expect that EFI will only increase reliability (haha funny isn't it) and maybe add ~2-3mpg. I also expect that with a 292 cam, header, 9.5:1pistons, 2.135L motor I'll have ~150/135rwhp. That should be plenty fast enough for a grocery getter that lives in a parking garage. I'll also expect to be able to maintain high 20's for milage hoping to stay within the ~28-30mpg range with a well designed ignition, EFI and combustion chamber.

The 4.11 is going to kill you. Carbs will kill you and EFI is only as good as you build it. Really be honest with yourself and your budget before you go down a road that will be dissapointing. Trust me that it's better to compromise up front and end up with exactly what you set out to build than to have to cut back on your 200hp race motor and end up with a 145hp half-assed motor.

HTH,

TJW

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....assuming I go EFI with a nice, big 58mm throttle body (E30 325is), should I still think about a cam swap? I really don't want to lose any fuel economy. What cam should I look at, if any?

Pick your poison. If you want power, put in a 300+ cam- tuned right, economy won't be too evil.

If you want economy, get a higher- lift but low- overlap cam. you'll not get as much power, but a good chunk of economy returns.

Frankly, put the stock cam in it and drive it. a 9.5 bottom end can handle a lot of different cams, and if you find that the right foot overwhelms the wallet, put a bigger cam in next year.

All the other stuff is, in fact, dependant upon the cam. Once THAT gets nice and fat, THEN you go looking at the rest of the car. There aren't really any major choke- points in a totally- stock car...

t

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allowing hp gains above 4 k rpm. Gear ratio 3.64 better if you drive alot on freeways. The EFI setup may cost you more $ than the savings of the expected increase of a few mpg.

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allowing hp gains above 4 k rpm. Gear ratio 3.64 better if you drive alot on freeways. The EFI setup may cost you more $ than the savings of the expected increase of a few mpg.

Hmmm....get rid of the header? Would the tii manifold do a better job?

Either way, I've got a 3.64 diff now and I think it'll stay in the car, instead of going back to the LSD 4.11 longneck. Thanks for the advice!

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