Tunnel rammed 23* 421sbc

[54chevkiwi]

Guys..

Im in the middle of a new engine build, i thought id post it here to keep a record of it, and get it out there for anyone else looking for ideas on something similar. I like to read peoples combos and the opinions on them etc so i thought some guys in a similar boat may like to read about this..

Shortblock was delivered ready to assemble from carl hinkson, just waiting on head studs, oil pump, gapped rings and balancer to arrive

421,
11.5:1 compression
Pump gas (93 in richmond VA where i am)
4.155x3.875
Mahle pistons
Compstar 6” rods and liberty crank,
SHP block
Bam solid roller .904 lifters
Ill probably add some lateral ports to the pistons and use a vaccum pump...

Top end and cam was done by eric weingartner..
248cc dragon slayers with wing option
2.77csa
2.125/1.575 valves, standard spacing
1.7/1.6 TD shafties
Welded and ported holley pro dominator tunnel ram
Cam specs 256/268 @ .050, .748/.704 lift, 110lsa
No idea what power and torque numbers will be and where... he did give me an idea of peak... If anyone wants to predict what itll make itll be fun..

Carbs likely to be pro systems xc carbs as per patricks recommendation, he says 760-780cfm flow..

It is meant to be a “drive to the track, run some 10s drive home.. drive to work if i feel like it” engine..
Does it need a TR to do this..? Nope.. but the tunnel ram is about fitting in with what my car was meant to be built as.. i think, my cars personality just needs it you know.

Car has a 3.89 35spline 9” wavetrack rear end, trans is a jakes performance d3 transbrake 4l80 and 9” 3500 stall. Converter and gears are left over from the previous engine, im kinda thinking of going for maye 4.56 rear and i dunno.. 5000stall... ill decide on that when i see where the power is after its dynoed..
Tyres for now are m&h 325-50-15 drag radials.
Exhaust im thinking maybe 1-3/4 stepped to 1-7/8 primary, 2” secondary tri-ys, 30” long...
the system will literally be straight out the headers to mufflers and dump behind the rear edge of the door, so at this power level, that exhaust being so short and straight i MAY get away with a twin 2.5” setup.. maybe twin 3” max..or a single 3.5” tail pipe.. i know how to weld so i might make all three and dyno each then run each to see what each does on MY setup...

Car has caltracs, split monos and sliders, double adjustable afcos front and rear and a 4” drop tube front axle with 4 link..

I asked eric to flow the heads with and without intake, he done me one better and done a video on them here..

https://m.youtube.com/watch?v=1_eMLf6-TFQ

Here are screenshots, top is the saenz bench, bottom is the superflow

B5D98577-B765-4ADE-B185-6EAC73600D6D.jpeg

Saenz bench heads with unported intake

5375C793-459E-4DCE-BE3E-9DE45BF43D50.jpeg

Saenz bench heads with ported intake

E12C161B-6EF3-4ECA-8B3D-06D2DFD156F2.jpeg

Ill update as i go along but may not keep up much between updates

[lefty o]

im sure it will crack 600 hp.

[F-BIRD'88]

Plan on using 100 octane unleaded.

[steve cowan]

Going to be a great project, I think Eric does nice work and I enjoy his videos.
In my opinion should make 1.35 ft/lbs per cube on pump gas around 570 ft/lbs
From my approx calculations you have enough CSA in the induction system so hp should peak above 6500 rpm so I personally think 700hp will be in the ball park.
Hopefully makes more

[steve cowan]

Plan on using 100 octane unleaded.

I ran my 3650 pound streeter last weekend for one pass (weather came in)
383 sbc,cast iron darts heads 182cc,240 deg cam,11.3:1 compression on pump gas,locked timing with 6al programmable 28deg
Ran it to 6000rpm in top gear 117mph,spark plugs are a bit rich from idling around but there is no sign of detonation on plugs or oil filter pre- screen or in oil filter.
Alot of people run higher compression with pump gas and its obvious there will be diminishing returns if you have to keep taking timing out.
Seems every time someone is running over 10.5:1 with pump fuel you have a panic attack??no disrespect intended.

20210402_084320.jpg

[F-BIRD'88]

28 degrees on that cylinder headvis a detuned state.
It wants 34-36 degrees at WOT to make max power.
Anybody can run around with the timing retarded.
Your luck will run out. Its just a matter of time.

Spending a ton of money building a high performance engine with all the goodies and a very agressive compression ratio and running it on cheap low octane gas and retarded timing makes no sense.. The engine will have a short service life and never perform to capability..
There is no free lunch. 11.5:1 cr needs about 100 octane on the street...on a 23° sbc cast block w aluminum heads and no electronic engine management system (EFI with knock detection).

[steve cowan]

Some engines make best power a lower ignition timing,I agree it is a balancing act, on this same engine with 10.6:1 compression with a flat tappet set-up I found it ran the best at 32-33 deg and track tested up to 40deg.the car ran the same up to 40 where mph dropped off.
To say a engine needs x amount of timing without having all the details at hand is like tuning by committee in my opinion

[77cruiser]

im sure it will crack 600 hp.

I think it'll crack 675 & 600+ tq.
Might want to rethink the exhaust.

[54chevkiwi]

I think it'll crack 675 & 600+ tq.
Might want to rethink the exhaust.
[/quote]

Yea thats a pipemax prediction for 7000rpm, not the 2.5” part, i just figured if its only 3 feet long total and straight why go overboard on the OD but im not married to it.., Gonna see if calvin will do this one too

shame, my last set of his headers are now hangin on the wall, guy didnt want them when he bought my 406..

[F-BIRD'88]

Some engines make best power a lower ignition timing,I agree it is a balancing act, on this same engine with 10.6:1 compression with a flat tappet set-up I found it ran the best at 32-33 deg and track tested up to 40deg.the car ran the same up to 40 where mph dropped off.
To say a engine needs x amount of timing without having all the details at hand is like tuning by committee in my opinion

Put some 100 octane unleaded in the tank and give it ghe timing and jetting it wants and run it . You will see the difference.
23 deg head sbc's all want about the same max wot timing.
Unless huge domes.

[steve cowan]

i have 2 x drums of MS 109 i will be testing over the next couple of months,i will report back.
OP sorry for the misdirection on your thread.

[F-BIRD'88]

You'll likely find it blends with your pump gas very nicely..
Good luck..

[54chevkiwi]

Burns spec’d tri-y headers 1-3/4 10.5” stepped to 1-7/8 10.5” primaries into 2-1/8 secondaries for 10.5” with 2-3/8 choke into a 4” single tailpipe or 3” twin pipes.

I really liked the fat mid range of the single pipe on the last engine.... but im thinkin i may go regulat twin pipes this time, i think itll have too much power already without needing every last bit

[54chevkiwi]

I took everything to work and measured it all....

Mahle pistons were perfect, 4.152 on all of them with the exception of 2 which were .0002 smaller.. pin bores were all perfect.. position was off +/-.0005 on them
BAM .904 solid rollers all measure between .9032-.9035
Lifter bores were all around .0017-.002
Connecting rod centre to centres were between 5.9994 to 6.002
Big ends were perfect with an extra .0002 at the parting line.. nice.
Crank was PERFECT. All journals perfectly round, at most is .0001 ovularity here and there (yep, now a word to describe the oval tendencies of a round thing) but thats within my personal margin of measuring error so who cares..
Mains had ZERO runout.. mains are .0025 on the button

Cam from comp was bent, journals 2-3and 4 had .0017, .0022 and .0027 runout respectively, i put it between centres at work and straightened it to .0012, .0017 and .0019, less than two was fine for me,

Everthing looks real good. I get beat up about tenths and millionths at work, so .002 is a mile to me.. in any case, its all perfect and the mock up has started

[54chevkiwi]

Rod to cam clearance hits rods 1 and 5 which i expected, its a .980 base circle..
theres a good .070 clearance on 2 and 6
Ill grind 1 and 5 and kiss 2 and 6 for good measure.