Build for Small Tracks

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Pops90

Member
I've got a Briggs animal that I believe was built for a limited modified class. (Target rpm is 7500 apparently) It is on methanol but still has a briggs carburetor on it. We mainly run small tracks around here, so I was wondering what the best route to take would be if I was looking for an engine with a lot of torque. I'm not looking for a high rpm screamer.

I haven't raced this engine yet, so I don't know how far off it is for our small block open class, but I assume it will need a bit of work to be competitive. Small block open around here is 300cc max displacement, and some tracks don't allow a billet head. Thanks.
 
I'm no motor guy far from it, but for a smaller track I'd want it good at high rpm, on a big track is when I'd want more what you described.
 
I'm with RP until you race it you really don't know .
If your racing againt 300 cc your down about 100 to start .
Your competition is a bigger question .
 
I would assume that it is a WKA legal alcohol animal - or maybe has a slight bigger cam, rod/piston combo with that low of target rpm. Most WKA legal animals will turn peak 7200-ish rpm on ovals, more on road courses.

When you say "target" rpm -- are you referring to peak CHP, or suggested peak rpm? HUGE difference.

Easiest thing to do to hop up your engine is a bolt-on carb.
Next would be a bigger cam, then a piston and rod combo.
Makes for a pretty nice HP boost and still keep it very dependable.
When you go to big bore, big stroke, then the reliability goes down as rpm goes up. It's a trade-off that most are willing to make when there's good enough competition that it's justified.

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Compression, Cam, Carb and CC's
Here's an easy way to boost the compression without expensive machine work.
920-207-9180
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Thank you gentlemen. My original line of thought was a stroker, but plan on camming it for lower rpm to help with dependability and cost. I'll run it this spring and see how far off I am.
 
Reviving this thread. I ran the engine once this spring and it was definitely down on power compared to the competition in open. I've been doing some research, and it looks like I have a Gen 3 block.

If I replace the carb, cam, piston and rod, is the block going to hold up? I'm guessing the primary concern would be how many rpm I shoot for. What RPM would you trust the block to?

If I am going to have issues, I would rather just sell the engine as it sits and get into a different class (I've been running Predator until now)

Thanks.
 
Post # 9-10 tell it all .
It's a reliable engine if you don't go overboard on the rpm .
Your wants and expectations are key factors , besides money .
A 308 cam , billet rod , high compression piston and carb should get you something too work with .
If your chasing a 450 then you might need something else .
Dare I say a 2Stroke .
It's a limited now so should have a rod in it .
 
flattop1 said:
Post # 9-10 tell it all .
It's a reliable engine if you don't go overboard on the rpm .
Your wants and expectations are key factors , besides money .
A 308 cam , billet rod , high compression piston and carb should get you something too work with .
If your chasing a 450 then you might need something else .
Dare I say a 2Stroke .
It's a limited now so should have a rod in it .
Click to expand...
Almost everyone around here is still running industrial engines and not mx engines, and 2 strokes are very rare to see.

I was thinking about the 308 cam, I just didn't know if a Gen 3 block would hold up to it or not.
 
If it has much of a cam at all it is being choked by the carb. If it was me and planning on buying a cam, piston carb and rod I would go with a new block and crank as well, save that thing for back up, try a bigger carb. If it is indeed a gen 3 it may have the old crank as well, and you are starting out with 2 strikes on dependability. By all means roll the cam, you might have only a quality stock class motor.
 
Chipg56 said:
If it has much of a cam at all it is being choked by the carb. If it was me and planning on buying a cam, piston carb and rod I would go with a new block and crank as well, save that thing for back up, try a bigger carb. If it is indeed a gen 3 it may have the old crank as well, and you are starting out with 2 strikes on dependability. By all means roll the cam, you might have only a quality stock class motor.
Click to expand...
Kind of what I was thinking regarding reliability. I'll probably put it up for sale and use the money on a clone. No animal classes around here and it aint enough motor for small block open.
 
IMHO the reason the gen 4 and then the gen 5 cam out was to make the block stronger. Duh
Depending on whos dyno it's tested on an open can make between 20 and 35 HP.
I know you know someone who knows someone that has a 50 HP Animal. Sure :)
Just because it's a small track doesn't mean a small inexpensive motor is going to get the job done.
You can bet there will be people that will be at the 300 cc limit or more and have done some exotic and expensive things to their motor.
I'm not trying to rain on your parade but, Open class means Open wallet.
 
Jimbo said:
IMHO the reason the gen 4 and then the gen 5 cam out was to make the block stronger. Duh
Depending on whos dyno it's tested on an open can make between 20 and 35 HP.
I know you know someone who knows someone that has a 50 HP Animal. Sure :)
Just because it's a small track doesn't mean a small inexpensive motor is going to get the job done.
You can bet there will be people that will be at the 300 cc limit or more and have done some exotic and expensive things to their motor.
I'm not trying to rain on your parade but, Open class means Open wallet.
Click to expand...
I'd rather find out now than after I've spent a bunch of money, so I appreciate the insight
 
Pop
This should be about having fun and enjoying the sport.
If you are having fun -- do it your way:)
 
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