High Compression L36 bottom + L67 SC (Corey's Engine Build)

Quote :

- costing less to IC rather than 9.4:1? That's a somewhat odd way to look at it. I can explain it by saying that doing a block swap is not a light undertaking, and an I/C install is less work to complete. The cost is slightly more, due to the pretty parts you have to buy, compared to just needing an L36 engine that can be had for as little as $100 plus gaskets/fluids. Gains from each, however, are different. The I/C will produce a better gain than just bumping compression that point, but that's not why this decision was made. Both of these items should be considered a positive upgrade for an M90 build, but we weren't doing something to add onto a build, it was to get it started & only one of those items has a rotating assembly, but the I/C can be bought later at his leisure, giving him the advantage of adding that mod on top of a more aggressive motor already.

Maybe I miss-communicated my question. What I meant was, assuming a blown L36 engine will need to use an IC to fight the knock, isn't that just extra cost compared to an L67, which can run the same boost level without IC? From what I know, you can compress the same amount of air/fuel in the L67 without as much detonation, because the static comp ratio is lower. With the effective comp ratio the same for both, the L36 wants to knock more, right?

Rest assured, no engine "wants" to knock. The L36 takes boost alot better than you'd think. My engine runs 12-13psi daily non-intercooled, and I drive an average of 22k a year (obviously not all WOT, but the pedal sees the floor on occassion). I don't suggest that for the run-of-the mill person, as it takes alot of babysitting & proper tuning and care to ensure one small overlook doesn't bring issues (single-hose gas pump with 87 mixing in the hose, copper plugs wearing out and causing pre-ignition, etc.). Of course, I can avoid the extra concern by running a 3.2 rather than 3.0 daily, but when you know you can safely squeeze that extra bit without knock, I'm sure many would take the same measures. Plus, it keeps me on my toes & I'm a stickler for paying attention to details on most things anyhow.

Your last comment is correct, though, in idea... the L36 does somewhat "tend" to knock with less of a mistake than an L67 block. In this case, you either have to not get aggressive with a pulley without monitoring like crazy, or simply find the limit and take a step back where it's guaranteed to be much safer. With an L67, you can go to tat limit & stay there with slightly less consideration for details.

I've seen 3.4 pulley'd L67's run up to 8-9* of KR for long periouds of time before fixed, and not end up chipping pistons. I've had instances during new setup dial-in's where I've seen knock levels that high on my L36 block without blowing the motor as well, but I definitely know each degree of KR seen, carries with it more weight than that of an L67 block.

I don't like to allow knock sensors to hear anything, regardless of how low the boost and compression is, for obvious power/longevity reasons. I'll be sure to have Corey keep you guys posted on the scan results as we get this going in the next couple weeks.

- Dave

I forget where I saw it but this is what I saw that made perfect sense to me, as I recal it. If you want to get huge amounts of power USING THE M90, you need to increase compression - huge amounts meaning more than the generally accepted +/- 400hp ceiling for the M90. If the blower can't actually give you the boost, you need to get the mechanical advantage elsewhere, ie compression ratio. If you switch to an alternate power adder (upgraded supercharger or turbo) to get your past 400hp, then it's generally more sensable to maintain 8.5:1 compression or go down to 8.0:1 because the power adder can give you all the boost you'll need at that point and the favorable thing to do is make the power adder do the work.


My own thoughts are that given the choice between using high compression + some boost OR using usual compression + more boost, option B should be less straining on the motor most of the time since boost comes on when you want it to while higher compression is inevitable. When you're cruising down the road with 10% throttle, the compressions still going to be full force.
Now obviously 9+:1 compression is not going to hurt the motor but as I see it, wear is wear not matter how fast or slow
Supercharged, high compression engines just don't have the record for longevity. I would not want to be in the situation where every unusual noise has me sweating beads in fear

Dave, I wish you the best of luck on this. I still have reservations about this direction, but I know if there's someone out there to do it, you're the man.

After hearing all of this, it seems to me that the reason for choosing an L36 block is solely to retain the M90 and have it work in its comfort zone, at the expense of doing a lot of work and adding an IC. It's a different approach for sure.

Personally, and this is just my opinion, if I were using all of the M90's potential on the L67, and wanted to increase power, I'd feel more comfortable swapping to a Gen V blower, or M112 and keeping the lower compression. This just seems like a lot less hassle, but I'll give Dave the credit for successfully tackling this project.

Are there any side-by-side comparisons, in terms of cost/power/ET, showing you get more out of using the M90/L36 combo than changing the blower or ICing a normal L67?

1998 Riv wrote:

Hey Dave, welcome aboard! Nice to see ya over here. (Dave is well-known among the MNClubGP guys)

Where all the cool PEOPLE hang out........ haha turtleman could be cool but he isn't a active memeber there

Um, I believe he signed up recently.

98riviera98 wrote:

1998 Riv wrote:

Hey Dave, welcome aboard! Nice to see ya over here. (Dave is well-known among the MNClubGP guys)

Where all the cool PEOPLE hang out........ haha turtleman could be cool but he isn't a active memeber there

I just went there to get the dirt on mr travis



JK ya I should get in there some more

Dave,

I'm glad to hear your explanations. I have often wondered what would happen if we just dropped a SC into a non-SC car, now I know it's quite possible... especially since the Gen3 blowers can be had pretty cheap!

I just wanted to make sure Corey knew what he was getting into. He mentioned over and over an engine build, and then out of the blue he's doing this... I know I could watch out for the surprises, I've been doing this kind of thing for 20 years, but it sounded like Corey was a little green in this area so I was worried about his decision.

Thanks for the reassurance.

maybe its just me, but I think the thought behind corey's build will work, but probably not without an intercooler setup.

It will have to use an IC, imo.

it will just not right away, i hope by late july i should

With what is planned, a 3.8 pulley will run safely (basic port/polish work on all top-end items & exhaust mani's, cat-less free flowing exhaust, tune for 11.5-12.0 a/f on 93).

If he does a cam, then we'll be able to step up the boost closer to where my setup is running. I'd only have him get a 3.4 or 3.5 with a VS/S1x/NIC/XP cam setup, although one more step might be possible (but reaching that edge I talked about, for 12.0 a/f and stock L67 timing). I'm hoping we come across another NIC sale, because that cam is great for builds like this, although I've worked with the others on these 9.4:1 M90 setups as well.

I promise you that by the time I leave it in his hands only, the car will run without KR while non-I/C'd. It may come in the form of leaving the 3.8 pulley and making more parts underneath more efficient to reduce heat generation, but it will be clean.

- Dave

What plans do you have for the transmission?

deekster_caddy wrote:

What plans do you have for the transmission?

Pulling the pan off the 3.29 tranny (to replace with a smooth/solid one), and will do a filter and toss some spacers & spring setup in the accumulators (if you know what I mean, you're all set). Going to run an '05 HD torque convertor/flexplate, and will soon swap in the HD diff/output shaft/CV end setup. It'll be identical to what I've been running for the past 2yrs.

- Dave

Good to hear. Again, just checking for Corey's sake. We all know how these stock transmissions respond to modded engines...

Right. If an issue occurs, just like I am avoiding with mine, then we'll address it... I/S - chain - P/S - and so on. I'll be sure to make him aware of when to get into the throttle in certain gears, for best acceleration & least shock to the tranny. There's a reason some folks can hold onto semi-stock build with more power for a tad longer.

- Dave

Dave...you have HPT right?

Set him up with Fuel Cutoff at 3000 rpm and spark cut off at 45mph. That should keep him under control.

BillBoost37 wrote:

Dave...you have HPT right?

Set him up with Fuel Cutoff at 3000 rpm and spark cut off at 45mph. That should keep him under control.

no lets not, the a kid with a mustang that has an ass whoopin in store

who want to take a guess at my 1/4 mile time when im done for this year. which will include cam,headers, and I/C with the tiny pulley. im hoping for low 14s to high 13s

palermocorey90 wrote:

who want to take a guess at my 1/4 mile time when im done for this year. which will include cam,headers, and I/C with the tiny pulley. im hoping for low 14s to high 13s

13.2 if its tuned by THE twin cities tuning authority..... but 13.4 if tuned by dave JUST KIDDIN.


but really 13.3 is what i had in mind...... of course IF you get traction

With everything your planning, I'd be hoping for a flat 13.

i just did it i ordered my Intense S1x cam

palermocorey90 wrote:

i just did it i ordered my Intense S1x cam

thats a HIGH FIVE:twisted:

i just had to get it, i mean hell its going to be tons of work doing this swap. why not do things right for a change

That's what I said when I handed over my CC number for one.

What is your closest track?
I'd let you borrow my slicks (15 inch rims) because I think you can run the size...but longer wheel studs are needed to run spacers with them.