Destroked 4.2L? Or stroked 2.8L turbo?

A

Anlushac11

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Setting up my 81 Mustang for Solo I/II and looking at rules for class H in the different categories it looks like I can run up to 4.0L for normally aspirated and 3.0L for turbo.

Which do you feel would be a better setup?

I was considering offset grinding a 4.2L (250 I6) to reduce stroke to get a 4.0L displacement or boring and turboing a 2.8L I6.

Any thoughts?
 
You're planning on running in the modified classes? Bring lots of $$$. Do you have any idea what you're up against? E typical E/M competitor who races locally and nationally (where he's competitive but does not win):

Lotus Europs chassis
Porsche transaxle
4.0 litre Rover Aluminum V-8

Another even more extreme example:

Ralt Formula Atlantic Chassis
Pontiac Fiero Body
Don't remember what engine (like it matters)

Take a look at the rules for Street Prepared and build a car to run there (no internal engine mods) or in Prepared (engine mods). You'll have a whole lot better time.
 
8) I know Modified is shooting a bit too high and being realistic is out of my dollar range.

I would rather run street touring or street prepared but I dont think the 81 Stang with I6 would be competitive without engine mods.
 
You said class H but there are different class that are combinations of letters and words like stock,street prepared, etc. The more radical the class the fewer letters there are. I haven't done any autocrossing in 17 years so things may have changed a bit. SO what "H" are you refering to.
 
I was mistaken. Looks like Street Modified uses SM1 or 2

Showroom stock uses HS (H-stock?)

Looking harder and longer looks like I wouild be more comfortable in Street Prepared. Similar to Street Touring but allows some limited engine improvements.

Printed off rules for Street Prepared. Will study these over next few days.
 
I know....sell me that notch and don't worry about it:P

I would just start with a stock 200 for now (yeah I know it will be slow but hey you have low end torque) and would on getitng a sorted chassis.
 
The biggest problem you're going to have with that T-top is chassis flex. If you build for a category that allows weld-in subframe connectors, you can reduce that problem significantly.

Even though you don't need one to be legal for Solo2, consider a roll bar.
They make the car safer (doh!)
They make the car stiffer, by a lot
Tech inspectors LOVE roll bars
They look cool.

Seriously, the engine is the last place to be spending prep money
 
I used to run in H Stock and D Street prepared in a Datsun 210. That was prior to 1990 though. Street propared engine changes were pretty much limited to what you could do without taking the head off. Most suspemtion mods were ok though.
 
In Street Prepared Im allowed to do port matching, balancing, and mill head to max listed by factory.
Im also allowed to run different carbs and headers.

I am very worried about chassis flex and intend to run a rollbar hoping that helps stiffen the chassis. There seems to be a question of whether im allowed a bolt in or weld in bar.

It also seems that jacking rails have been banned now too even thought they were original equipment on convertible Mustangs.

But I can run the 11" front brakes, still trying to find out if the rear discs are legal.

I already have the front and rear swaybars, wheels, tires, brakes, and a 3.45:1 7.5" rear. I have a 8.8" disc brake rear ready to install if legal.

Right now car is a c4 auto but Im still waiting to hear back on trading a set of 17x9 4 lug Cobra R clones for a T5 install.

I was looking at street modified, which allows most everything I want to run.
 
SM is pretty much run what you brung, as long as it has a full interior. If you want to play around with your (modified) car and have no delusions about being competitive, it's probably where you belong. Pretty sure you can weld in a cage in SM but you need to check that

SM is the home of such exotica as a 'Vette with a carbon fiber body. There are people who will spend virtually unlimited amounts of money for a trophy.
 
That it would.
As nearly as I can tell from reading the rules, the only typical Foxstang mod not allowed in SM is the replacement of the front subframe with a tubular unit and coil-overs. This is no great loss since the front fenders typically don't live long taking the increased load of coil-overs in a road-race/auto-x car.

As I read the rules you can weld in sub-frame connectors which do not incorporate "lateral bracing" which I read as jacking rails and you can weld in a GCR legal roll cage such as would be used in a Prepared or Modified category car or bolt in a Street Prepared legal roll cage. The trick as I read it is that the weld-in cage has to be GCR legal. You really need to e-mail the SCCA Solo Dept for clarification on that point.

One of the biggest handling imrovements to be had in a Foxstang is to relocate the battery from the heaviest corner of the car (LF) to the lightest (RR.) There's a perfect spot just behind the RR wheel well. If you do this, invest a few extra bucks in a TI "Clix-On" circuit breaker and put it in the hot line of your battery as close as possible to the battery (mine is mounted on the battery box.) Tech inspectors love attention to detail and they love overkill. When they see a car that is obviously over-prepared in terms of safety equipment, they often give a quick pass on the tech stuff assuming that the car is either completely legal or way too trick for them to catch it. (This only applies at local events. At divisionals and Nationals, they check everything...but they still love overkill on safety devices.)
 
Anlushac11":mzq25oe5 said:
Street modified would also allow me to run Mike's aluminum head :twisted:
Click to expand...

If it was painted,had a 2bbl intake, with a motorcraft 2150 carb and a stock type ford air filter housing, maybe you could sneak it into a lower class.
I mean most people never heard of a alloy head for a old ford six. :wink:

Just watch out for tech inspectors carrying magnets. and that can be fixed with iron shavings mixed in the paint. :wink:
 
There really is no lower category where it could be competitive.

In H Stock, very, very few modifications are permitted and the I6 Mustang has to run against things like the Civic Si and the Mazda3. In other words, no chance in hell.

In E Street Prepared pretty significant chassis mods are permitted but very few powertrain mods. Among the competition would be both V8 and SVO Mustangs as well as the Talon AWD Turbo and the Mazda Speed6

In C Prepared, powertrain mods are allowed but the cars are no longer required to be street legal. Lots of minimum weight gutted interior Mustangs and F-Bodies with full race chassis and 400 HP engines.

SM is pretty much an open class but it probably presents the best chance to be competitive
 
8)

I just wanna go play :wink:

In SM it says the block has to be a production block from a North American engine. Thats about it. All other engine mods seem to be legal.

D. Drivetrain and related components (induction, ignition, fuel systems,
etc.) are unrestricted except for the following limitations:
1. Engine block must be a production unit manufactured and
badged the same as the original standard or optional engine for
that model.
Click to expand...

Says nothing about the head.

The 250 was available in Mustangs til 1973 so that means it was a production unit manufactured for that model.

In Street Prepared Im allowed to use production equipment from other years of same model but documentation that it was stock is my responsibility.

I also want to use 90-93 big opening fenders and a '87 fiberglass bumper and aluminum bumper supports (Just needs a 1/2" spacer. Also getting rid of the 1/4" thick boiler plate steel alternatror/AC bracket. That would drop almost 50 lbs off very front of nose.

Already have a trunk mount battery box
 
Okay, here is my "uber pwnage" combination. Its based on an idea I floated in 2002 with an X-flow head, but it'll be better with the D8 or Classic Inline head as its non cross flow, and allows space for a killer blower.I discussed in I'm Gonna Blow my Budget post in the hardcore formum many moons ago.

Grab a 250 block and grimnd up two custom 250 cranks. Both should be stock 250 US cranks which are offset grind it to 1.676" jounal diameter, and index the stroke to 3.46". Then reweld the crank up to 2.126", and cut the crank back to a 15 thou fillet radius. Add 6.21" Ford 300/4.9 forged rods, and have the gudgeon/little ends replaced with the Chevy 0.927" bush.

I used used old TRW 305 V8 /229 V6 forged pistons (there were three part numbers to choose from, and they are around if you know where to look), or perhaps the KB 101 22 cc, KB 145, 12 cc, (Keith Black / Silvolite hypereutectic) , 22cc to down to 12.1 cc. The deck is 1.561 now quoted but there used to be a 1.531" deck version used to be available. They can be skimed to suit the 250 block, at 1.561, they will hit the squench area unless you run a 60 thou gasket

wf120_small1.gif



Here it is compared to a 258 Jeep piston

pistn2.jpg


Then run a D8 iron head with three Holley 4412 carbs using a welded adaptor like the Falcon Six Handbook suggests, duplicated three times.

3V2300_1.jpg


TripleTwinBarrelUnstagedCarbsonSix.jpg


Use all there Falcon Six handbook tricks on airflow management, and go for the bigger SI valves Classic inline supply.

Then create a bleed back carb system like David Vizard suggested on page 167 of Reworking Fords SOHC engine. That uses a good mechanical fuel pump to deliver fuel to the carbs, and no float bowls, but a special standpipe made of bunday tube . Fuel surge is eliminated by fuel cell foam, a requirement for stock fuel tanks in most racing classes. The foam is piut into the float bowl, and the stand pipe sucks the bowl dry. You can runa car on a 45 degree angle using this combination. The float bowl is sucked dry by a Facet or Carter electric fuel pump, and float level is controlled by a Holley main jet of varying size controlling the incomming fuel. No injection, no calibration issues, just simple math to make it work


Take each carb, and hone out the 1.375" venturi to anything bigger than 1.4375" using a woodern broom handle mounted on a power drill, and 3m fine grit sand paper. Hand linish the correct venturi taper, and block off the power valve using a stock Holley PV eliminator kit. Calibrate it like three DCOE 42 Webers, and get a cam which has power at 5500rpm, revs to 6000 rpm, and is about 290 degrees, 225 degrees at 50 thou, and has a lift of about 510 at the valve with 1.75:1 FE roller rockers.


Care of Jack Collins years old triple 1-bbl 250 he helped make. Its got had made triple adaptor, handwelded dual out iron header. The general look of the engine will be like this, but you'll have to help find potential owners for some custom Fox headers that Mike has been looking at for some time

Fox2503veng.jpg


Fox2503vexh.jpg



Your power should get to 300 hp at 5500 rpm, and about 300 lb-ft at 3200 rpm. Set CR to 8.6:1, a perfect 0 deck engine with a 200 thou trench in the piston which should be great for spark travel. Use a waste spark igintion system from a Ford Explorer 4.0.


From http://falconperformance.sundog.net/compcalculator.asp

Input Values:
Number Of Cylinders 6
Bore Diameter [inches] 3.736
Stroke Length [inches] 3.46
Combustion Chamber Volume [cubic centimeters] 62
Head Gasket Compressed Thickness [inches] 25 thou
Head Gasket Bore Diameter [inches] 3.81"
Piston To Deck Clearance [inches] 0.002"
Select Piston Type Dished
Dish/Valve Relief/Dome Volume [positive cubic centimeters] 12.1cc
Volumetric Efficiency: 85%
RPM: 5500

Results: (Based on single carb, log head, no cam mods, no indpendent runner tuning )
Displacement, [cubic inches] 228
Displacement, [liters] 3.7
Static compression ratio 8.9:1
Cubic Feet per Minute required @ 5500 rpm, [cfm] 309
Estimated Horsepower @ 5500 rpm
Assumes altitude of sealevel, barometric pressure of 14.696 and 60° air supply to carburator 172


Independent runners, wild cam, the right carb size and jetting, there is better than a 50% boost in this kind of optimisation


Once you've got that running with a close ratio rip shifted T5 gearbox and a 3.45:1 diff, you can then bolt a nice big 284 cid per revolution 4/71 blower on the side. I've got a Wade 208 cid per revolution blower which will do the same thing.

The engine should then see 500 hp at 5500rpm, and 500 lb-ft with 13 pounds boost and no intercooler.

This was my original design concept for my X-flow 228 cube engine in the early Naughtees. I'd like to think I'll do it once I've got my other projects finished. :wink:
 
8)

Actually looking at the Chevy 305 piston and 300 I6 rod idea I am finding numerous sets of eight Hypereutectic 305 pistons in stock bore with dry film lubricant coated skirts for $120.

The crank work now seems to be the expensive part.
 
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