Low compression methanol engine help

[Fastwing]

Hello all,
I am primarily looking help designing a cam, but also anything else that may help me make more power.

Ok, here's the situation. We race an entry level sprint car class that requires us to run an engine package that consists of a 350 CI Chev engine with 9.5:1 compression max. You can also run a Ford 351 or Mopar 340 / 360 but everyone runs the Chev. The rules mandate a stock or speck Scat crank, stock or spec 5.7 rods, flat top 2 or 4 valve relief pistons, 76cc cast heads, and a flat tappet hydraulic cam. We can run one of two aluminum single plane spec intakes (Weiand 7546 or 7547-1), and a gauge legal Holley 4412 2bbl methanol carb. Any 2bbl to 4bbl adaptor allowed with a max height of 1.375" including gaskets. Headers not exceeding 1.75" od tube and straight collectors, no merge flow, no tri-Y. No port matching allowed. These are basically a Wissota Midwest Mod engine with a spec intake on methanol.

Our engine as it currently sits is a 355 Chev with 993 heads that have 1.94 intake / 1.6 exhaust valves. . We run 1.5 stamped rockers, 3/8" screw in studs, guide plates, and hardened stock spec pushrods. The crank is the spec Scat 9000, the rods are stock 5.7 with 5/16" ARP bolts. The pistons are Mahle 2bbl. We run the taller 7546 intake, an adjustable adaptor, and have both a Willies and Quick Fuel carbs. We also run a K&N Flow Control air cleaner. The headers are an equal length 1.625 to 1.75 step with a long smooth transition 3" collector. The ignition is a Magnito, solid stainless core wires, to Auotlight alky plugs.
The cam is Jones Cams piece. It has an LC of 107 +4 (103 Int) that I advanced further to 101.5 when I converted to this class. The installed event timng at .050 is IO @ 21BTDC, IC @ 43ABDC, EO @ 55BBDC, EC @ 9ATDC. I have worked with Mike for years and he has helped us run very well but this engine package is pretty unique. Mike and I have some ideas but I thought I would throw it out here for discussion as well.

A few thoughts I have had are to go to less overlap with a 108 or 110 LC cam to prevent over scavenging the cylinder. Another idea is to run more lift and duration on the carb restricted intake side. I can run a 1.6 rocker so thought I would dyno it both ways if we stick with a single pattern cam. I also plan to dyno it with an adjustable timing set and try advancing and retarding. The other thing I want to try is running the shorter 7547-1intake as it has a flat floor which I believe will help with fuel distribution over the pent floor with center diver I have now.
I have read slot of great info on the board and trust the brainpower here will have some very useful info on this topic. Thanks in advance folks!

[pamotorman]

the "G" forces in the turns causes some cylinders to run rich because of fuel spill over unless the is a divider in the intake manifold when running a carb on methanol.

[Fastwing]

Thanks Pamotorman, we do run a center divider in the current manifold. That is not and option in the shorter one I am considering.

[twl]

Why use methanol with a compression ratio that could work easily with gas?
You don't get any of the advantages of the methanol, and all of the disadvantages.
I don't understand it.

[Fastwing]

It's just the way the rules are written as it's a sprint car class. We have r to run methanol.The same engine actually makes the same or slightly more power on the methanol , likely due to the better intake, and is very easy to cool. We don't even run a fan in the sprint car where we ran a fan, shroud, and triple pass radiator in the Midwest Mod. Given the choice, I would not run the methanol.

[lada ok]

Why use methanol with a compression ratio that could work easily with gas?
You don't get any of the advantages of the methanol, and all of the disadvantages.
I don't understand it.

Other advantages are intake charge cooling and and the calorific value of meth at the right A / F ratio is better than petrol

I don't know if you should get to bogged down with cam selection,

I don't know if anyone here knows your rule book ,( is there any thing online we can look at ) but there is free HP all over the engine, more than likely, and they add up

bigger things might be HEI dist but with ecu spark control, manipulating the carb venturi size

Biggest gains are pretty much always in the cyl head

[Ks Fats]

110 lobe separation for sure; as an experiment install some 1.3 break in rockers on the exhaust only to see how the engine responds. Sounds like you are on a stock rocker rule but you could do this in a hot -lap session. 1.6 rockers on the intake generally are a positive move, depends on the cam. I'm sure Mike would provide some feedback on this. If the rules do not restrict you to 3/8 studs upgrade to 7/16. Ford rockers are 1.6 and meet the stock rocker requirement(they are cast rather than stamped). I have used a fabricated oil deflector plate to tie the studs together using longer set screws in the poly locks and nylock nuts but have also been told to remove it at some tracks; depends on the tech guy. If it is in the budget a trip to the dyno will give you a leg up with dialing in the 2bbl to the sprint.

[Fastwing]

The rules are located here. I am running the Package #1 B-Mod type engine. http://winged.umsprints.com/downloads/get.aspx?i=236424 I am going to dyno the engine again for sure, I do each year to dial in any changes and to break it in.

Why the 110 lobe separation? Curious as to your thoughts here. We are on a stock stamped rocker rule but I have ordered a set of 1.3 break in rockers and a set of Manley stamped 1.6 ratio rockers to try as well. My dyno plan was to do as you described, try the 1.3's on the exhaust, and the 1.6's on the intake first, then on both intake and exhaust. I agree, it's the little things that add up. The heads flow as well as is possible within these rules.
Thanks guys, please keep the thoughts coming, the season is close and I am excited to see if I can squeeze a little more out of this package. The LS engine option may be next year but for this season, I am committed to the current engine package.

[wyrmrider]

very interested in your results
do not overlook the 1.65 Pontiac rockers
if they let you relocate the studs then 1.7 BBC rockers
fill this checklist out to see if you missed anything and post any additions back here
http://jonescams.com/circle-track/

[Ks Fats]

Widening the lobe separation (to a point) made more power; I experimented all the way to 112 ( the dyno was happy but the driver didn't like the acceleration off the corner). I speculate that since the primary restriction is the carb at the head of the flow and given the elasticity of the limited flow, the 2bbl stuff responds less to the exhaust during overlap. Most rule packages state no porting on the heads or intake (similar to yours); working on the spacer/adaptor can help even out the egt's. A 4/7 swap can help that too if legal. Years ago they used to give the 9 to 1 late models a weight break and working to equalize the cylinders and maximizing cylinder seal made them so competitive they took away our weight break; your situation is very similar. Sorry for the late response; I had a hair pulling relationship with an old 6 jet carb most of the evening. B.T.W. Don't be surprised if you end up with an "unorthodox mix" of rocker ratio's across the engine, you'll probably find differences from cylinder to cylinder.

[ddave]

Just info: the car has to come off the corner... These things don't shift gears. In gear or out of gear: direct drive.
They can start a race at 2000 Rpms or lower or higher/ depends on leader and track size.. Engine has to accelerate a wide rpm range..
Alcohol helps keep the engine cool verses gasoline-

[lada ok]

Your biggest gain will be on the induction side ... which means air flow corrector at the top of the carb, looks like the rules don't mention not being ablr to knife edge the throttle blade smooth the aux chokes and barrel and chokes, the exit side of the carb should match the spacer exactly , ( ' o ring and not a paper gasket here ) and a nice underside radii to meet and match the top of the mani, doesn't say how think gaskets have to be, ... + / - IN gasket will move the mani up / down , possible HP gain

[Fastwing]

All good points ddave. Starts are usually around 2000-2300 rpm, and racing runs from 4500 in the bottom of the corners to 6400-6600rpm at the top of the straight away. Pulling about 6 inches of vacuum at that rpm. The engine currently makes 421tq at 3900 -4500 and 384hp from 5100-5400. Still making 371 at 6000. I wouldn't mind trading 10 ft lbs for 10-15 hp at a around 5400-5800. Better yet, keeping the tq and adding the HP.

[ProPower engines]

So what I am hearing is the torque is up with the cam ahead and the HP goes up with the cam the other way.

I just did 2 weeks of testing this very thing and if you don't need a fan the engine ain't working hard enough.
I am an alky junkie and the 2bbl stuff had years of practice with and every driver I worked with liked the grunt coming off and the car was geared to suit the drivers talent. If the driver can be faster with torque and a less gear try working with it for a bit. The chassis has to handle the extra grunt as well and dirt is easier then pavement when wheel spin has to be controlled to manage shute speed but to carry that all the way around is even better.
If the car turns well enough to handle wide open all the way around then take some gear out til it pushes coming off.

On asphalt we do reverse cool the engine and the nose is closed in for down force ( non winged cars) and the fast guy I work with is running a single row double pass rad and never get above 200 on gas ( we wish the tracks would allow alky but no) in a 40 lap main at 6900-7100 and he's on the gas all the time as it lift turn gas again

We found and lots will argue the point but we are down to having cams ground at 101. Not using a what ever and advancing.

Get with mike on this but you may go through a couple cams but when you get it right you will be the top dog if the drivers any good and the chassis is right.
JMO