Tony @ Mamo Motorsports

Guys,

Thought I would share some recent results of a more unique build I was involved in lately. I wont get into a bunch of all the back story drama surrounding this engine (massive amounts of delays and setbacks....most of which was beyond my control) but for all the aggravation this engine gave me going together it made up for it with a really smooth day on the dyno. It was like this engine just wanted to waste no time finally firing up.....LOL It primed almost instantly, fired up without a fuss (we loaded a tune from a previous engine I tested at Westech that was obviously close)....took throttle beautifully and just had an awesome cackle and an appetite for RPM that even surprised me the guy that designed and built the combination.

It was basically an LS3 based stroker engine with a 4.100 stroke....in fact it is actually a 426 CID build as this block had an oddball finished bore of 4.067.....not the typical 4.070 a 427 would normally come with (I was enlisted to turn a shortblock from a popular vendor into a complete engine with all my Mamo Motorsports top end goodies and down the rabbit hole we went from there....ended up rebuilding the entire engine and buying custom pistons for the odd bore size etc.). It was a good thing I had the opportunity to build it from scratch as I feel the piston to bore clearance is really critical on an engine like this that really pulls the piston out of the short 5.500 long factory sleev with a 4.100 arm especially (I prefer to build larger bore 4" stroke 427 based combinations with sleeved blocks that are even longer (5.750 - 5.800) for much better piston support at BDC and the better longevity that scenario creates).

I ended up hand fitting every piston to each bore as there were was about a .0005 difference from the smallest bore to largest (I wetsanded some of the skirt coating to keep my piston to wall all the same) keeping the rock to a minimum but being careful not to make them too tight as well. Some of the other features of this engine that are noteworthy is moderate cam duration for this displacement and SCR (just under 12 to 1) for good driving manners (cam was a 243 / 254 on a 114 + 3). This cam has about 20 degrees of overlap which is good area to be in for a dual purpose street strip engine of this size.

We could have went larger but the results show that was really unnecessary as this engine pulls like it has a much larger stick in it. Two things I attribute to that.....my MMS 260 LS3 heads which move 390+ CFM through a modest sized 260 cc intake runner (literally the same size as stock but it flows almost 70 CFM more than an OEM as cast LS3 head.....big airflow and huge velocity.....the win win combination every time). And coupling this build with a mid length FAST which while probably hurting the lower and peak torque numbers 15-20 ft/lbs, certainly helped the power up top and really helped extend the usable curve with the modest by some folks standard cam that we chose.

The curve this engine produced actually kind of surprised me as I wasn't it expecting this type of combination (long stroke in a short sleeve block) to look so good up top....the power and torque curve from this build were both insanely flat and while the shorter runner cost us a little peak torque, we still managed 575 or so ft/lbs (so not lacking there!) and another 100+ past that number in peak power that just hung on! In fact it was only off its peak power figure at 7200 by an HP or two.




Steve Brule (the dyno operator at Westech) asked about the rods and I mentioned they were SCAT I-Beam with 8740 bolts and to be honest both of us were unsure what they are really rated for so we kept the pulls to 7200 (my customer made some phone calls the following day after the test and based on the feedback he got from Scat and potentially another source feel 7500 is still in the cards with a reasonable safety margin).

This engine is going to be insanely fun in the lightweight Pro Touring Box Nova its being installed in. I think the car only weighs 2900 lbs and with the way this engine is going to scream up top.....man....I hope I have the opportunity to drive it!! (he lives in CA and is not that far from me!).

Its late.....Im sure I have more to add but I will revisit the thread and fill in any holes in the build I may have left. I think I covered most of the big stuff with you guys.....before I call it a night with this first post, here are some pics at my shop of the engine coming together!























Alright....Catch you guys later!



Regards,
Tony

Che70velle

iTrader: (6)

Impressive as always Tony!

NAVYBLUE210

Tony Excellent results (as usual) from an under square long stroke 427".

Interesting Comparison with a Richard Holdener 427" with TFS LS7 Heads,
MSD Intake, & Larger BTR Stage 4, 247/258 on the same WesTech
Dyno that made 19 LESS HP & 11 more lb', Compression not given.
That curve falls much quicker due to the Longer Runners in the
MSD VS the Mid Length Fast I believe, despite the Larger bores
and similar airflow between the MMS LS3 & out of the box TFS LS7
Heads and slightly larger cam. The curve is posted in Power & Performance News, and also in patrons "New Products Thread"
Would be cool to see side by side or overlaid, beyond my
Computer skills, LOL.

Darth_V8r

iTrader: (4)

That's a cool motor! I'm with you in that I prefer the engine be oversquare. I find the LS in general seems to do better when bore>stroke. I've been wanting to see some results off the AFR260 ls3 heads. One big reason I've never been a huge fan of the 3.9x4.0 383.

big hammer

Cool build. Looks like it wants to carry up
Top well too

Ls3 heads FTW

Bad_AX

Tony, this is one of the coolest builds I've seen in a long time. Kind of counter intuitive but it worked out really well. Congrats on an impressive engine and power/torque curves. How much valve lift for this combo? Any pics of the pistons? Are they flat tops or have some dome to get the compression? What rings are you running? You must be managing quench and burn very effectively to run 12:1 compression. Can you talk about this aspect in more detail? With 20 degrees of overlap, is reversion going to be an issue or are you getting high enough velocity though the intake to negate it?

Thanks!

carbuff

iTrader: (8)

Quick question Tony...

I thought your MMS 260's flowed 410+? I'm curious what is different about this setup?

Very nice result, should be a lot of fun!

Che70velle

iTrader: (6)

Bryan, perhaps your confusing these 260 ls3 castings with Tony’s 265 Ls7 castings, like you have? Just thinking out loud...

carbuff

iTrader: (8)

Ok, I feel silly now. I read this as an LS7 architecture, but you're right, it's LS3... I should have read more carefully. Thanx for setting me straight.

Tony @ Mamo Motorsports

Thanks for the props....I was excited to test it because it was a little different!

This will be a 91 octane build with some Boostane or Torco added to the mix to improve the quality of the fuel.

I do have a tight quench....excellent chamber design so it takes less timing than a stock ported casting to see the highest output regarding cylinder pressure/power and the fact we have 20' of overlap allows us to get away with even more static CR. Honestly this combo would have ran great on straight 91 a few tenths lower static and in the cooler weather might still run really well on straight pump, but we wanted to maximize the static compression as much as possible and my customer was willing to spring for the octane boost as needed (more an issue in the hotter summer months etc.)

Honestly this much overlap in a 427 isn't very excessive at all and should run really well all around....I knew with the high flowing heads and the shorter runner intake the top end of the curve wouldn't need much in the way of camshaft to help it carry well up top (did even better there than I expected honestly!), so I purposely kept the cam timing reasonable and even installed it a few degrees advanced to help the bottom of the curve some. I was looking for a balanced curve....more flat but making alot of power everywhere and something that wouldn't quit up top.

The end results met pretty much all my expectations and exceeded in some regards as well. It really is going to be an insanely fun motor to drive....especially in a lighter vehicle like the owner of the car is installing it in!


Yep.....there you go

My MMS 260 is my LS3 product.....the MMS 265 being my LS7 stuff that flows a touch more....both are 12' valve angles



Regards,
Tony

jhshnh

HighspeedLean

iTrader: (2)

The pics of the intake ports w/rockers is of a LS7 head, the bottom pic shows LS3 heads bolted to the motor. Caught me by surprise also

lazerlemonta

Get rid of that pulley on the Mezier kick *** results Tony!

spanks13

iTrader: (5)

Tony, you sold me a mid runner FAST that you ported about a year ago for my LS2 swapped RX7. I came and picked it up at your shop. I haven't had a chance to build my engine yet...another project car displaced mine out of the garage hah.

This dyno sheet has me VERY excited for my next build. That is exactly the curve I want for my 2800 pound mazda, and makes me feel like I'm very much on the right track. That torque curve is a thing of beauty...

I was also happy to read your thoughts about compression and 91 octane...I'm spec'ing mine at 11.5:1 and plan on running straight 91.

I had very similar duration numbers in mind for my cam, but I was thinking more about 110 LSA with a 107 ICL. Lots more overlap, same duration.

What do you think that'd do to the shape of the curve, and the operating range of the engine while keeping duration the same?

DietCoke

iTrader: (18)

RX or miata? A big stroke LS won't fit in a typical miata, the stroke interferes with steering rack position. You're limited to 3.75" or so.

JimMueller

iTrader: (9)

How does the AFR 260 LS3's massaged by you compare to your MMS 260 LS3's? How would one decide upon one over the other?

spanks13

iTrader: (5)

RX7. The GM Fbody camaro oil pan works with a short hair thickness between the rack and the pan after correcting the steering geometry. My car has been running/driving for 3 years.

Why would a stroker interfere with the steering rack in the miata? What oil pan is required to swap into a miata, one without clearance for a 4" stroke?

DietCoke

iTrader: (18)

An F-body pan wont fit without a manual rack, if that gives you any idea. The clearance just isnt there.

Tony @ Mamo Motorsports

My program is very similar on both castings.....intake flow is really close.....exhaust port on the AFR is larger and flows a little more when Im finished working on that casting. The actual castings are a few pounds heavier as well so the AFR would be a no brainer with boost....N/A could go either way....guys that sweat a few pounds saved here and there would opt for the TFS casting assuming the build is landing somewhere in the three digit range versus the four digit range....LOL

That's the abbreviated answer to your question I guess.....both products come from me highly detailed with all the same "fit and finish" so to speak and are both really an excellent choice.

Hope this helps!

Cheers,
Tony

VINCE

iTrader: (1)

Very nice package!!! For years you have delivered. Congrats!!!