Yes the 4 lb limit was set for durability reasons. The bottom end would not take anything above that "reliably" the platform was an ls1.

 

So now looking back at my logs from a couple of projects and chatting with a few friends, it sounds like the upper limit for the LSx block, crank, rods and connecting hardware used for the LS1 and the higher compression LS6 is actually closer to ~625rwhp.

With a couple over 700rwhp on a stock block that only needed a oil breather cap because, like us, the stock crankcase ventilation was designed for vacuum and atmospheric pressure induction only.

One of them only required 13psi with an automatic transmission, so that would put into the 800 HP range at the flywheel

YouTube - 717rwhp Corvette Z06 Twin Turbo





Shown on this LS1 are two Mitsubishi Gasoline Turbo each capable of pushing nearly 500rwhp worth of air at only 18psi! All on a .84A/R undivided turbine housings, so they spool fast, as you can hear in the video. Each one has the equivalent of a nearly 3L 4cyl feeding them exhaust.

Which seems to be corroborated here by several Corvette owners, many reporting between 12-14psi, but few discuss the compressor or turbo this was done with, almost all of them incorporate my favorite pump gas power adder, Alcohol injection!

http://forums.corvetteforum.com/c5-f...stock-ls1.html

So again max boost is relative. Most of the owners in that thread note they only added a cam and the springs to go with it.

As long as you have an efficient compressor and/or turbine and housing to match, some nice cool burning fuel and a decent tune, there is no reason your LSx can't take years of abuse above 10psi. If you are that concerned do a 1/3-1/2 Hard-Block treatment, ARP hardware and fasteners top to bottom, a nice Fel-Pro MLS headgasket and some Clevite or ACL rod/main bearings and call it a day.

Again, it is all about having the right supporting and complementary mods. The Fit's engine is no exception. Treat it right, and we should be able to massage some impressive and streetable numbers from it.

NA is not necessarily the solution to reliability either.

 

As a tuner acquaintance of mine once said...
"If you want a reliable engine, stay stock"

Engine swap would be the next best thing, but good grief, the cash outlay for a K...

 

Na is not the solution but I would rather keep an engine designed to be na just that way. It's really a preference if only that. Those guy's running that power on a stock bottom ls1 must be really conservative driving them daily, or they just don't drive them daily and they are track cars. The latter is most likely the case. Yea tell me about it that k swap.... Only way I see myself doing that is if a k20 was conceived by the holy spirit and left at my front doorstep....and alll other supporting mods

 

Just a rule of thumb almost everyone could agree with boost and high compression don't go hand in hand. It may not be 14:1 and require some c-12 fuel. But it's still higher compression than engines that normally run boost.

 

A Methanol or E70/85/98 user might disagree, but for pump 93 oct (or less) gasoline users who like to run alot of spark advance at WOT this is true.

Boost is only part of the equation though.

You can run 11.5:1CR on Pump 93 and say 18* Peak Timing and 15psi with 11.3:1AFR, or you can run 13* timing and let the turbo spike to like 20psi with 11.7:1AFR for example.

All setups are different of course, but this is a scenario I've seen more than a few times. Gains were marginal between the two methods, but even running ~5pts leaner and ~5psi more boost, knock seems to occur less often than when that extra 5psi was replaced with 5 degrees of timing.

Even after things should be considerably heatsoaked after a a bunch of WOT pulls, like tuning a VE table from scratch..

Pump gas seems to perform better under boost more than spark advance in my experience, assuming everything else is the same including atmospheric temps, efficient charge cooler and overall engine configuration.

E85/98 howevers seems to like both high spark advance (>20*) and high pressure ratios, like 3-4bar! Even on 11.0:1CR or 12.0:1CR, runs safely really lean (>12.5:1AFR on gasoline scale UEGOs or >0.87v Lambda)

I should also note, this is done on setups where stoich AFRs are calibrated to 14.1:1AFR to account for the 10% Ethanol they mix into gas around here. So that ~12.5:1AFR is actually even leaner compared to straight gasoline stoich @ ~14.7.

And there are alot of turbo 4cyl guys running 93 w/ Meth or straight Ethanol blends around here.

Year round daily driving +35 PSI on big compressors..

One of the motors I am tearing down for a long con rod drag project is a NA version of the Turbo motor in my Laser. All I plan on doing is drilling and tapping into an oil passage for some under piston oil squirters and putting in a PCV and catch can.

Compression is actually going up compared to the NA or turbo version, 9.8:1CR because of a custom Mahle piston 6mm raised wrist pin to accomodate the longer con rods and stock stroke. Would be 10.1:1CR but I am planning on re-decking the head and using a (thicker than stock) 1.6mm MLS head gasket to bring it down a bit.

It's the moldy one on the left that I picked up for $40 dollars lol

 

I see that alot e85 and lots of boost. Is it because e85 takes longer to burn in the cylinder more so than even 93 octane. Is it a colder burning propelant/ignition source...one of the fastest street cars down here was a Honda running e85 and boost.

 

E85 (105 octane) and other blends bring a bunch of benefits to the table for performance applications. You just need a whole lot of it, and a fuel system that can deliver it. Not only is there more exhaust volume produced compared to gas because of the requisite extra fuel needed for a given unit volume of air, but the combustion can take advantage of a couple extra degrees in reaching MBT vs gas.

This means more torque with the added timing, but in the case of a turbo application, the extra gas volume, which is still a little hotter than diesel exhaust spools turbos very fast, which also produces more torque.

Ethanol which is 115-116 octane, actually burns faster than gasoline.

Especially when slightly rich for power production:

Flame Propagation 1.0:1 1.1:1
Gasoline --------- 26 cm/sec ------- 30 cm/sec (max about 31 cm/sec)
Ethanol ---------- 41 cm/sec ------- 45 cm/sec (max value)

It burns much colder, it also manages to cool combustion chambers as much as 230*F just on introduction and heat absorbed in vaporization! Some people even forgo charge coolers and instead just rely on injecting ethanol or methanol in the upper intercooler pipe, it is that effective.

Ethanol, being an alcohol also brings it's own oxygen!

I want to emphasize again that you need a lot of fuel Because you always need to be able to dump in more fuel than "necessary" at a moments notice to cool things off or worse so you don't run catastrophically lean.

So for comparison:

Here are some comparisons of stoichiometric fuel mixtures for different fuel blends:
======== stoichiometric AFR ===== max power rich AFR
Gasoline ---------- 14.7:1 -------------------12.5
100% E-85 ------- 9.73-9.8:1 ------------- ~ 9:1 - 8:1
100% fuel ethanol - 9:1 ------------------- ~ 7.2:1


For my relatively mild goals (at least in the DSM world) with my current 1G DSM has the potential to flow almost 69lbs/min or 630-675whp worth of air, and when you need between 25-45% more Ethanol than Gas, I end up needing 1450cc/min injectors, 2 rewired aftermarket fuel pumps in series, an -8AN fuel line feeding a -10AN filter and rail. This of course required an adjustable fuel pressure regulator (intended for boost to rise/fall at 1:1 ratio) with a -6AN return line.

Here are some links you should read if you want to play with Ethanol

MegaSquirt
Injectors and Fuel Supply

NASIOC
E85 fuel FAQ - NASIOC

Honda-Tech
** The E85 Thread ** - Honda-Tech

Honda-Tech Real world back to back tuning example, tuning with two fuel maps (literally the same stuff I do on my other cars )
E85: Some real-world data - Honda-Tech

I am even in the process of installing a JDM H22 into a Prelude for my buddy who's original USDM motor is seeing only like 40psi wet on two cylinders at the moment

Honda Tech Some Turbo Specific tuning info
Some more E85 tuning... turbo this time - Honda-Tech

I have more but they are from private forums, some of which unfortunately come at the cost of an expensive PCM like ECMLink or MegaSquirt/AEM/HalTech/Racepak etc. with some information being proprietary and not allowed to be shared to the public, like on NABR and a couple others.

 

Yea e85 does burn quick which is why those cars that run on it get dismal mpg. I thought the more octane in the fuel the slower it burns which is why you get better mpg/performance out of 93 as opposed to 87

 

Well they get poor mileage because you are dumping in 25-45% MORE E85 than you would gasoline for the same amount of air.

There is also less energy per gallon for ethanol than gasoline. Octane doesn't determine flame front propagation though, so higher octane can burn faster or slower than a given hydrocarbon soup with a lower octane content.

For a VERY thorough discussion on the merits of Regular V. Premium, here is a thread where we beat it to death, resurrected it and killed it again:

https://www.fitfreak.net/forums/2nd-...our-fit-6.html

I would start at page 6. In that thread I have included a chance to download some tuning software and really learn what goes on inside an ECU.

 

Ethanol has oxygen which need more fuel to burn. Richer mixtures burn faster because more fuel molecules are closer together, Result is more Hp and poorer mileage. Not getting into premium argument again but Flame speed correlates to octane. Higher octane has faster flame speeds but has a slight delay and burns the end gases before knock can occur because lower octane fuels the end gases ignite before the flame front gets there. Engineering-Fundamentals-of-IC-Engines-WW-Pulkrabek

Running premium in most cars will cause the car to be more efficient and produce more power depending on the additives (oxygen,toluene) mileage will go up. Mtbe is a perfect example high octane with more btu's than ethanol.

 

A couple quote from the book Engineering-Fundamentals-of-IC-Engines-WW-Pulkrabek

The octane number of a fuel depends on a number of variables,some of which are not fully understood.Things that affect ON are combustion chamber geometry, turbulence,swirl,temperature,inertgases, etc. This can be seen by the differencein RON and MON for some fuels, brought about by different operating characteristics of the test engine. Other fuels will have identical RON and MON. The higher the flame speed in an air-fuel mixture,the higher the octane number.This is because, with a higher flame speed, the air-fuel mixture that is heated above SIT (self ignition temp) will be consumed during ignition delay time, and knock will be avoided.

Fuel components with long chain molecules generally have lower octane numbers: the longer the chain the lower is the ON. Components with more side chains have higher octane numbers.For a compound with a given number of carbon and hydrogen atoms, the more these atoms are combined inside chains and not in a few long chains, the higher will be the octane number.Fuel components with ring molecules have higher octane numbers. Alcohols have high octane numbers because of their highflame speed.

 

my friend just sourced a K swap for his Integra he's almost done and only down $2500 but he didn't go for the K20a.

 

Actually, they have for race engines. But for street engines its pretty much a waste as the feds close in on modified engines and emissions standards. Its already true for many states and soon will have all 50 that an emissions test is required to get inspected and licensed. Mods like you want simply fail emissions.

 

Um.. what? Big cams actually have a tendency to increase "natural EGR", and it is all in the tune as far as whether you will pass emissions.. a cat. converter is a must as well. Anything over like 2.5" will be approaching useless at idle though. You can also lean burn from idle to 3k ( just not too lean to avoid excessive NOx production)

 

You need to work on a few engines increasing hp over 100 hp/liter and still meet emissions requirements on pump gas. Just not happening that easy or inexpensiovely. Take a good look at porsches and Vettes..

 

That is what I do... Many of the projects I work on come from the factory with 100hp/liter or greater (4G63T for example ) .. I am quite well aware what is involved.

Any work I do on an OBD2 street car has to be emissions compliant, at least in Cook county, IL.

Or you have to pay for a $430 minimum repair every year you fail, till you are compliant.

Most of those, including a couple of my own, have far bigger than stock cams. Some on the order of 30* more duration, steeper ramp rates and like 0.1xx" more lift.

Once you have the tuning gear all you need is to pony up for the gas you will use driving around to calibrate, so it's not that bad really.

Porsches and Corvettes are not expensive just because of the tuning aspect. Though I can't think of any OE form Corvettes besides the ZR1 that is seeing more than 100hp/liter.

What is your experience in this area?

 

as supplier of parts for more than 40 engines for manufacturers production line. When you build one engine but not a thousand, its not that simple or inexpensive and when you put reliability in it the quality testing and standards eat that 'easy' extra hp up. That tuning is not easy over the working range of the engine. And what's your experience with emissions testing? just what tests and evaluations did you perform? And over what length of operation? SAE J1711 et al?

 

No need to be hostile..

And I have built more than one engine thank you. Reliability comes down to the parts and tolerancing for its specific use as well as measures put in place to extend that reliability like an external oil cooler, revised HLAs and oil pickups. Or grooved bearings where necessary.

Just like shimming and REM/ISF or Cryotreating a trans, it is all in the build and preparation.

My experience with emissions testing is if the final product does not meet emissions compliance the owner or myself have to eat a $400 dollar fine in cook county if they do not pass.

We have to pass all CO2/NOx tests, etc. at a state run or board certified facility, meeting all legal requirements for an OBD2 car.

OBD1(1995 models and earlier) however doesn't matter anymore, at least here.

You just can't make a sweeping statement like "aftermarket cams mean you won't pass emissions" and not expect to be held to task for your claims, so don't get pissed at me when I ask for clarification and how you have arrived at this conclusion.

It's like when the discussion of OpenLoop v. ClosedLoop operation comes up and every internet expert immediately starts asserting you will by default get poor fuel economy locked in OpenLoop.

There is a lot of grey area in tuning, and there is alot of variation from one set up to another in the real world.

 

Quite correct and thats he problem when complying with SAE J1711 et al. And then there's budgets.
Look at it this way, manufacturers aren't dumb. They really want the most that can be gotten with emissions and mpg market needs for 50,000 miles. If you don't have to meet all 3 there is a lot of leeway. But thats coming to an end. I suspect it will be only a couple of years before such long rnge tests documentation, even in Cook county, that 'souped up engines like we did in the eighties even are long gone.