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What is the most power achievable on 87 octane?


mutantZ

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Couple nights back I read a few threads dealing with detonation resistance by reshaping combustion chambers, pistons, etc. I was just wondering what kind of documented HP have members been able to achieve on their L motors using the crappy stuff? I know anyone who is at the dyno is prob not going to be running 87, but just for kicks I was wondering if people have been able to hit the 300hp mark. Please list what types of mods done to prevent the dreaded L-boom.

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Less timing, less octane, more BOOST! I've heard of BBC making 1,000+ on thier 87 octane tune and then 1,500 on good gas with some timing. My friend makes 290 at the wheels on 87 octane with 21 psi, and 290 at the wheels with 93 octane and 16 psi (this is in a 1.8t). It is all in the tune!

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Don't want to sound like a ****** but... unless you live in a remote area where only 87 Octane is available, why would you want to bother building a performance motor to run on 87? If it is a matter of the price difference maybe you should not be driving a classic car. But even so as the above poster alluded too, building a 300hp motor for low octane would cost quite a bit of money. Most likely more than the savings at the pump would cost you. Just my 2 cents.

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Why build around 87? Because when you're driving cross country on your special car and find the last station out of premium you can still fill and go like nothing.

 

Tell me, why would you build to 91 instead of 87? Seems to me common sense says build to 87, run 91 and NEVER DETONATE. Then again, my car hasn't broken or blown a head gasket since 85... Running anywhere from 5 to 21 psi... So what do I know? BTW, I tuned to 85 octane MoGas as that was what we had. Coming here to the states allowed me to bump up a bit.

 

I've seen more people blow their engines getting greedy on 91 instead of being happy tuning on 87 then running 91 as insurance. I like to actually DRIVE the car with looooong intervals between parts failures.

 

Maybe that's why?

 

And if you think building only 300HP on "low octane" is somehow expensive... What do you think I have in my dyno-best 375Hp setup (but which usually always runs at 350?)

 

What's expensive is greed. More boost. More power. I know guys who have paid more for HEAD GASKETS to make their high-octane motors run than I have in my entire engine. In fact, I remember what I paid for it: $25, Two 25Kg bags of Calrose Rice, and a 1/2 Gallon of Segrams Whiskey. For that I got a JDM L28 N/A with 24,000 miles on it along with the complete maintenance history. The Triples were $242, the turbo manifold surge tank and turbo under $500 at the time.

 

Considering Glidewell turned 288 at MSA this weekend and his setup is period comparable, I don't see where the big expense comes in tuning for 87... Other than he said he ran race gas and has a terrible surge box design... But I digress.

Edited by Tony D
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While you do have some very valid points Tony , I'm not going to argue that. But the OP made no mention of a turbocharged setup, so I would have to assume without further info he is referring to a N/A setup. In all your experience have you seen somebody make 300whp NA with low enough compression or timing retarted enough to run 87 octane safely?

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Low octane gas actually acts VERY nicely with modified NA motors, provided you keep the TIMING out of it at the lower RPM range. F1 doesn't run fuel that would be considered "high octane", they simply out run detonation. We can learn from their philosophy if we care to admit how it can apply to us.

 

It's not hard to make a L motor that revs to 10k. Does it cost? Yes. But plenty people have done it and are still doing it. Having a head that flows up there is a whole different matter of course. Point being, most detonation will be observed under 4,000rpm in most NA applications. With good tunable ignition you should be able to pull enough timing out of the high load, low RPM areas of the map to compensate for the lower octane.

 

Look at the modern luxury or sport cars. They usually say something to the effect of "use premium for full power" and in most cases where there's actually published figures by the manufacture showing the HP difference between pump gases it's rarely more than 3%, in fact I've seen plenty where the spread is hardly over 1% power difference. This is what you can do with MODERN TUNING CAPABILITIES. If you want to push the limits of 87 octane, be prepared to spend money on at least the brain that controls the whole thing.

 

Oh, and regarding turbo configurations and all that, I agree with Tony completely. It really doesn't take much money to get power from a L28ET, even on 87 octane. And I'm 100% behind the philosophy of tuning for the "worst case scenario" and then letting the good scenarios be insurance. Too many guys are tuning their E85 setups without considering that when winter rolls around they'll probably get a winter blend of E70. This is a huge reason why the GM vehicles have a fuel sensor to measure the blend and adjust accordingly, not to mention the headache of mixing partial tanks...

Edited by Gollum
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While you do have some very valid points Tony , I'm not going to argue that. But the OP made no mention of a turbocharged setup, so I would have to assume without further info he is referring to a N/A setup. In all your experience have you seen somebody make 300whp NA with low enough compression or timing retarted enough to run 87 octane safely?

 

I guess the fact that he's asking such an open ended question involving a 300hp L engine lead us all to beleive he was talking turbo. Or maybe because out of all the N/A builds featured on this forum, even the most expensive ones I haven't seen 300whp on any pump gas, much less 87. IIRC Dan Baldwin was close, but not over 300 on pump juice.

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Good responses so far guys. I mostly asked the question in terms of engine efficiency, or combustion efficiency rather. I only stated 300hp just cause that seems to be the number most questions get asked about (how do I make 300hp L motor etc). I know the modern GM truck engines run on 87 octane all day and make more hp per cubic inch than their stock counterparts from around the time of the L series engines. I know it's 5.3 liters to 2.8, but they do make more power relative to their older counterparts. I was just wondering if anyone has modded their combustion chambers/pistons to make anywhere near the hp of the mystical 300hp mark, but able to run on lower octane (NA or turbo) and not have a serious detonation issue.

 

I don't plan on running 87 octane at all, but it was more of tech/bench racing question to see what other people have achieved.

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This ignorance of octane rating has persisted for years. Gene Berg was a big proponent of much lower than conventional practice for street engines in air cooled VW's. He showed dyno differences between the same engine optimised at each compression ratio from 7.0-10:1.

Big difference was detonation and rod bearing wear due to detonation...

His philosophy was with the EXTREMELY SMALL penalty in actual under-the-curve horsepower and torque compared to an engine that would run 150,000 miles+ vs. 30 Dragstrip Runs before needing rod bearings, you were far better off designing around low octane low compression. He actually would change heads to race, and swap back yo drive home!

 

The big thing is the consensus is the most economical way to reach 300RWHP is turbo. Can you do it N/A? Sure. What would you lose on that engine tuning for 87 compared to 113 C16 Racing Fuel? 20-30 Ho? 10%?

 

Seems to me most people have a problem handling 150-200HP, much less 300. I doubt they will notice much less be able to adequately utilise that power properly.

 

The difference in performance envelope between the car with 270 vs 300 RWHP is going to be minimal.

 

The longevity from lower compression, and being able to run most premium fuels with NO FEAR of detonation: PRICELESS!

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Oh, and BTW, Ive just re-read the post and it says "list the mods needed" -- last I checked, hanging a hair dryer on an N/A Longblovk still was considered "a modification"

 

I wouldn't dare touch that can-o-worms with a 30 foot chin spoiler. But let's see how well I can dance around that fire.

 

The issue with "this is how to make X power" is that it goes entirely against the grain of truth and dumbs down the truth to a simplified version of truth. This might sound very philosophical but lets examine.

 

 

10 years ago when the honda scene was at it's peak internet forums were crawling with "stage 1 power" this and "15hp gain list" that. In reality people were simplifying something that should never be simplified. Now we have car guys that say things like "how much power should I get from a stage 1 upgrade to my L motor?"... An engine is a combustion driven air pump and has about a million variables to consider when designing one and most of those areas can be considered when modifying one for a specific purpose. If you were to ask me "how do I make a 200whp L motor?" I'd say "how do you make breakfast?" Those questions have a lot more in common than you might think.

 

 

A much more targeted question is something like "what's the most economical way to reach 200whp without a turbo?" and then let people know where your skills are at so they know what they can suggest. For example, while one person asking that question might have next to zero cylinder head modification skills I might suggest sending a head out to someone like Paul and tell them to build an appropriate head. If the person were more adventurous and ready to take on a challenge, well then I'd be more likely to recommend doing the shaved P79/P90 and then doing a good job to match the intake, exhaust, and cam arrangement.

 

Even in that scenario there's no "right" or "wrong" answer in a lot of ways. You could use just about ANY cylinder head for the goals mentioned, yet people will tend to recommend one over another. You could also go after building up a crazy bottom end and then just slapping the right intake exhaust and cam on a stock head and rev up to the moon to make the target power. You could make it on carbs or EFI.

 

Let me just think off the top of my head all the variables that can be considered when building an engine:

 

Valve size, valve stem length, valve stem to head taper, valve seat angles, valve seat surface widths, valve material, valve spring pressure, valve spring weight, valve angle, valve bowl shape, runner shape, runner area, runner radius, chamber size, chamber shape, spark angle, spark depth, spark plug design, spark plug heat range, spark plug wires, distributor/coil design, cylinder head cooling channels, cylinder consistency, cam lift, cam ramp rate, cam duration, lobe center, cam timing, lifter design, lifter friction, lifter geometry, piston weight, piston crown thickness, piston to wall surface, piston ring count, distance from piston deck to 1st compression ring, thickness of piston rings, material of piston rings, surface of ring grooves, wrist pin diameter, connecting rod length, con rod material, con rod balancing, con rod shape, con rod bolt size/type, crankshaft (you could write a college school book on this subject and just be scratching the surface), plenum shape, plenum volume, runner to plenum taper/radius, exhaust primary diameter, primary length, exhaust restriction, etc etc etc

 

 

I could go on for days on that paragraph but limited myself to 10 minutes. There's huge sections I didn't even touch on, but that's just to wet your apatite on how infinite this subject gets. So next time someone asks "how do I reach these goals with my engine" just remember that they're probably severely limited in what they actually want as an answer versus how infinite the subject really gets. The truth they want is small, while the real truth is many times larger.

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I've been told I make answers overly complex, and because if that I'm a bad guy-some sort of know-it-all. I've been told things aren't as complex as I make them out to be most of the time.

 

I'm trying not to know as much as I do, so I'm more like a fat purple dinosaur that sings happy songs and dances with the kiddies in a non threatening, non pedophilia way.

 

I'm thinking of repainting my 260 Purple & Green...

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I'm a fat purple dinosaur that sings happy songs and dances with the kiddies in a non threatening, non pedophilia way.

 

 

 

Hold on and I'll be around your place shortly with my wire restraints, rusty knives, battery acid, electrodes and thumbscrews....

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Okay, now we all need to get in on a group buy for some window vinyls with a picture of The purple dinosaur with a caption that says "Beware Of The Dinosaur"

 

Is that what the D stands for Tony? Tony Dinosaur?

 

IMO, simple answers have their place, but I try to not over-use them for the sake of someone's ignorance. If people want to stay narrow minded I don't waste too much energy trying to get them to see beyond the simple solution.

 

If I was a car guy who wanted a simple solution I'd have just gotten into mustangs or camaros where power comes easy and parts are just a wallet away and people can tell me how to spend every dime of it.

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"IMO, simple answers have their place, but I try to not over-use them for the sake of someone's ignorance."

 

If I said that..... Ooooooh the furor!

 

I love U's, they were not in Z's....

But it's still in the Nissan Family

With the L, the G, the A and RB, too...

C'mon Hybridize you two!

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You mean there isn't a bolt on combustion chamber? :P

Seriously though, I guess I was asking an oversimplified question. I was just wondering if anyone made any significant gains while tuned for 87. It could be 130whp, but 300 was just a figure I pulled out of the ether. It was just a curiosity seeing as how alot of people look to run race gas or e85 and tune for max hp, I was just wondering if anyone went the other route (of sorts) and tuned for lower octane. I'll go back to my google dyno sim now.

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Over 300 in an L28ET with regular old 87 octane pump gas.

Over 165 in an L28NA with regular old 87 octane pump gas.

 

Two personal daily driver examples. Go back and read my original post about compression and how much you get. It's not as much as you THINK you will get, and in most cases all you do is set up an engine that REQUIRES high-octane fuel.

 

What's a 5.7L Chevy making on 87 Octane these days? 330+ REAL HP? That's a 'significant' bump from the unreal 145 you made back in 1975...

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