Street Stock Speedway

[Clevo120Y 815]

I have been getting into the speedway down here and it's a great form of motorsport, class rules make the development of engines a real challenge and that makes it very interesting for me. Anyway I was talking to a bloke who runs a crossy XF in the street stock class and he now has me building and developing his engines which is great, top bloke and just gives me free open slather on what I want to do engine wise as long as it's within the rules. The challenge was to make the car competitive against the newer injected cars that have a grip on the class but sticking with the carby crossflow. All the racers down here said it couldn't be done so the challenge was on. I have been involved with the car for 3 rounds, the first round was just some tuning and setup with the engine that was already in the car, setting up rockers, timing, fuel etc etc. the car went really well and finished in the top ten of a 24 car field in the final, he was a bit too excited with the extra power and reved her a bit hard and hurt the engine so he I got to build a new one for him, Full rebuild so I flowed the head, picked a cam that was actually smaller than what was in it already as I think it suits the engine and rev range better. Motor went together nicely no real problems, ran the cam in and raced it again next round. First heat I asked him to just take it a little easy and load it up to bed rings in and shit, he was happy when he came back in and thought it was producing good power lower in the rev range which is what I was after. Heat 2 he was having problems that it wouldn't make power under 4500 and we discovered that the dizzy had broken the center signal wheels pin, so the dizzy had advanced itself and made it run poorly, we missed heat 3 while we fixed the problem by repining the dizzy centre and got the timing as close as I could just to run in the final. Started the final in 12th position and finished 4th. Not bad for a new engine with no real tune in it yet.

The car was dropped off to my workshop before the next round for me to go over the engine and build a new dizzy for it that won't break. Everything was micky mouse and no damage done by the broken dizzy. I went through and studded both the intake and exhaust manifolds to make things easier when pulling it down and putting it back together, set all the timing up again with a conservative tune because I couldn't make it to the track for that round and I just wanted it to be nice and safe/reliable. Well he finished 2nd outright in that round and was pumped with how the car performed, a couple of the faster cars of the region were at a different event on the same day so I still think we are about the 4th fastest car in the region at the moment which is still pretty good I rekon. 

Next Saturday we are racing in Albany again and I'm onto some more development work, I have done some flow testing on the stock aircleaner assembly and carby. The stock webber carb flows 261cfm and when you put the aircleaner on it drops down to 235cfm, it is the same with or without the aircleaner in the housing, what this told me is the restriction is the amount of air that can be pulled through the original snorkel, so I used a holesaw to make some extra breathing holes on the opposite side and had immediate gains, this is something that can be done to a stock car for nothing. The flow went up to 251cfm just by giving it more area to breath from. Next I will be cutting the top off another aircleaner housing and welding it to another base to increase the height of the housing over the top of the carb as this allows a taller aircleaner to be used and gives extra height above the carb which allows for better flow.

I will also building a custom webber carb during the week for increased flow and hopefully the AFR meter will be here during the week so we can fine tune jetting at the track.

 

 

[eattsie9 350]

wow thats awesome, go the crossy

[slydog 7,873]

Well done Sean...looks like you have to tune the driver now.

[ando76 4,354]

great work sean - making power in restrictor class racing sure takes some brain power but its rewarding when it comes off.  PM me If you want some suspension percentages for the XF.  I imagine street stock does not allow coil over adjustment but there are ways to make changes without coil overs. 

[Clevo120Y 815]

Tony that would be great, I know nothing about suspension setup, tyre pressures etc etc. will shoot you a PM later today mate.

The injected guys that said it couldn't be done don't talk to me anymore hahahaha

[Clevo120Y 815]

Sly I'm the last bloke to tune a driver LOL he always go's on about having to improve so that's good. He got enough points during last rounds heats to start on pole in the final but he had a couple of average corners and ran 2nd instead, either way we are faster every meet so that's the direction we want to be going in, state titles are in 3 rounds time and if we can get in the top 10 of the state then we have done well.

[Clevo120Y 815]

Here is my youngest boy, he looses his mind everytime there is a race car in the workshop LOL. He knows all the blokes names as well and everytime the phone rings he says "is that Wombat or Wolfy or Corky?" "Are they bringing the race car over?" He can't get enough I have to drive him around in the front yard in them HAHAHA

[Campo 869]

Good stuff mate. I've got an EF street stock over in victoria

[ando76 4,354]

Nothing better than touching up an injected car in a carby car.  brings a smile to my face every time.  My boy loves the race car as well and gets in it whenever he can. 

 

The car looks very well put together by the way.  keep up the good work.

[Clevo120Y 815]

Well I got started on the webber carb today, full rebuild and some work in the venturi's and stuff to get it flowing better. I take the end of the screws off that protrude on the other side of the throttle plates.

 

 

Then I clean up the overhang that is in the small part of the venturi and clean up the throats, blend all the sections together and open up the gaskets a tiny bit so there is no gasket overhanging in the throats. I also sand the boosters a little and polish them up as well as the venturi's.

 

 

Then put the carb together, The carb flow tested at 274cfm, a 13cfm gain. Dosen't sound like much but it is around 5% which is quite good for not changing the dimensions of the carb.

Then I started testing with the aircleaner assembly. modified housing with aircleaner inside went up to 260cfm. then I thought about raising the housing with a spacer to gain some space above the carb, this got flow up to 263cfm.

 

 

Then I started to think about how the air was entering the carb, one thing that I have learnt with flow testing is that air doesn't like to enter something with a sharp edge, that's why you put playdo at the entry to make a radius entry, so why not see if the same would work for the top of a carb??? well it does make a difference. I tested the carb first by itself and with a radiused top flow went from 274cfm to 285cfm!!! that is a huge gain so I'm now thinking about how to make a top for the carb that makes a radius.

So testing with the aircleaner now with the spacer and the radius on the carb the whole lot pulled 274cfm. To put this into perspective I started with 235cfm with the original carb and housing and now I have 274cfm, a 39cfm gain and staying within the rules of the class. WINNING!!!

 

[ando76 4,354]

Nice gains there Sean - it is the little things that make the difference in restrictor class.  You can also mill down the back side of the throttle butterfly as well to get a bit more gain.  same as the top side on a holley.  I think that is still within rules in production class. 

 

A set of ram tubes for the weber is probably out of the question because of the standard air cleaner assembly. 

[NZXD 2,328]

Keep up the top work, I love reading this stuff.

[Clevo120Y 815]

Thanks Tony and NZXD. I'm starting to get my head around the speedway thing, the sport must send people broke, the amount of carnage every round and they have to fix it all hahahaha. We will see what gains in power these changes will make this weekend, I'm off to see if I can do a simple way of putting a radius on the carb top, will let you know how I go.

[eattsie9 350]

wow thats really cool how a few little changes make such a big improvement

 

Sent from my GT-I9100T using Tapatalk

[ando76 4,354]

It costs me $600 a meeting - if nothing breaks. 10 meetings a year. Ouch. Oh and I am classified as a budget racer. i.e I will use my race tyres for up to 6 meetings. Most only use them for 2-3.

Oh yeah - you get really good at fibreglass repairs and welding as well.

[Clevo120Y 815]

 

Well it works mint, pulls 280+cfm. a nice tight fit and all I have to do is push it on right before I close the lid of the aircleaner. Will have to seal it with something but I will just try it out this round.

[slydog 7,873]

Looks fuckin sik bro...making all the right moves on it so far.Props to you...I'll even have a Jimmy can to celebrate for ya.

[Ando81 2,949]

Great work bro, looks like you're on a winner!

[dougie77 789]

Thanks Tony and NZXD. I'm starting to get my head around the speedway thing, the sport must send people broke, the amount of carnage every round and they have to fix it all hahahaha. We will see what gains in power these changes will make this weekend, I'm off to see if I can do a simple way of putting a radius on the carb top, will let you know how I go.

One thing my dad used to say was"what's a good way to make a small fortune motor racing???? Start with a large one"

[Clevo120Y 815]

^^^ HAHAHA that is spot on, I'm just happy that I'm getting paid some cash to play at the moment.

The top worked out well and I'm keen to see how dramatic the improvements will be, Thanks to Tony who has been giving me an education on car setup which I will be putting to good use this weekend. I have found a guy who will scale the car for a carton of piss so I can get some starting specs for setup with this car.

[Outback Jack 6,352]

Nice work man, maybe a 3D printer would be cool for making these carby intake adapters. I like the routered one....... but I'm a caveman, I would of made it with a chisel and lots of swearing ..... lol

 

Jack.

[ando76 4,354]

Carton of piss for the loan of use of a $1200 set of scales - awesome work - you won't look back - just a word of warning tho - scaling becomes addictive and you can spend hours mucking around with them - oh but the results are well worth it. 

 

If you need some set-up sheets for scaling let me know and I will email you a blank one which you can use to print off heaps of copies - trust me you will need them.....

[Clevo120Y 815]

If the top works well I might look into doing one for a holley and see if there are gains in flow and gains in the real world, then I might get some cast.

Tony that would be great if I can get those sheets off you mate, again cheers for your help and I'm sure we will be faster with your input. I'll send you a PM.

[slydog 7,873]

Fuck them bro,make something for my Webers instead It doe's need some new trumpets TBH but we may have to angle mill the manifold face and carb face a tad to get some more room but thats where my porter comes into the picture...mate...buddy...pal

[slydog 7,873]

If the top works well I might look into doing one for a holley and see if there are gains in flow and gains in the real world, then I might get some cast.

Tony that would be great if I can get those sheets off you mate, again cheers for your help and I'm sure we will be faster with your input. I'll send you a PM.

 

Without pissing in your pocket bro it is very good to see someone using there bench to solve issues not just make chev's faster if you get my drift.Some common sense thinking and some of your time and you have found out some stuff others will go there whole life without knowing.

 

Seriously props to you Sean.