GreenPhoenix

Been running it for a while now and there's a few things I've noticed. It sems like power tapers off between 5500-6000, with the gearing I have I'm just at the end of the straightaway when that happens. I've thought about retarding the cam a little but I like how it pulls coming out of the corner. Unless I change my gearing I'll probably just leave it alone. Also if I roll out of the throttle (opposed to letting off the throttle all at once) it hits a weird spot at about 3/4 throttle where it seems like it wants to speed back up even though I'm getting out of the throttle. It acts kind of like a part throttle lean/surge type of condition, but like I said I'm at the end of the straight going into the corner so this only happens for a split second. As far a the lightened flywheel goes it helps the motor come up faster and it feels more responsive, I don't feel like engine braking is affected very much. In this type of racing application I think a lighter flywheel is a good idea and if you have the capabilities to lighten a stock flywheel yourself that's even better. Keep in mind that the flywheel will need to be balanced after any lightening has been done. Not very many races left this season but I'll post any information I can about how it is running or any problems I experience. Feel free to ask questions if you have any.

4b316

Hi,thinking about building a toy for next year.i have been running a FI 2.5 ranger the last 4 years,winning 15 races and two championships.I beleive I have taken the 2.5 as far as I can and other guys are copying my truck and catching up.I am thinking about building a FI toy or nissan,leaning toward the toy as far as ease of parts.What are you running for suspension in the torque bars?I,m not totally out of the loop on toy setup as my truck owners also has a toy in the stable and runs 4wd bars.Are you making enough power now?Where are they beating you now?Our rules are basically the same but we can run a 350 holley carb if we want.Would you have gone with the carb if you could?What kind of gear are you running?We are running a big half mile blacktop track with big corners so never really getting out of it,running the ranger about 6200 with 4.56 gears.

GreenPhoenix

I've never messed with any Nissan engines but as easy as the Toyotas are to work on I wouldn't go with anything else. I run stock torsion bars up front. We run a low banked 1/4 mi dirt track and I think they are a little soft. There are aftermarket torsion bars available from several companies for 2wd applications, sway-a-way comes to mind. I'm not sure how they got the 4wd bars to work in a 2wd, they are different lengths. There are also several different diameters to choose from but not all companies offer all diameters. If i remember right; the spring rate of a torsion bar increases by the square of the increase in diameter. I haven't gone to bigger bars because I've got my current setup working well for my application. Adding stiffer bars up front will meaning changing all four springs and possibly all four shocks, essentially starting over. My gearing puts me between 5500-6000rpm going into the corner depending on the track. The stock fuel injection setup runs out of steam around 5500 but will turn to 6200 if you want it to. Long intake runners and limited cam duration are most likely the limiting factors. If you are consistently operating above 5500 I would steer away from stock fuel injection. Without substantial porting peak torque as dictated by the intake port cross section will be between (again, if I remember right) 3000-3500rpm. This torque peak is independent of being carburated or injected. Peak horsepower will be around 1500-2000rpm above peak torque. Just things to keep in mind when building one of these motors. I am contemplating going to a carbed setup for next year but the feedback I've gotten from reliable sources tells me that the injection setup runs much smoother on the track. The Holley is much easier to tune than the Aisin from what I've seen, also much more aftermarket support for the Holley. We are required to run open differentials so it usually comes down to throttle control, drive off-corner and corner speed. There is only so much torque that can be applied before one tire spins and you lose momentum. If we get a sticky hook-up track you can apply more power but the guys with poor setups are also hooking up better. Not quite a wash but its not as obvious of a difference who has the most power. Your record sounds similar to mine.

4b316

He is changing the back brackets to compensate for the different length bars.He is running the toy right now at about 6700 at the end of the straight at another track,a short 3/8,s with tight corners.Thats with a 350 holley,40 over,mild cam,alum.flywheel,wacked head.No porting and I think they have 4.44 gears in it.If he got ahead of me ,I couldn't get by him and vice-versa.I am thinking about building about the same bottom end as yours and if I go carbed,with a 20r head.we have to run a stock intake,do you have a peference for that?What dist.to run?Cam for top end?Since we run blacktop,we have found that the open rear works best(as we have to run all same size tires)but this year might have a new rule for stagger so might run locked.Waiting for this years rules to come out.

Dirt Driver

Which Nissan and Toyota engines are you actually allowed to use?

GreenPhoenix

When you're taking about 4.56 and 4.44 gears I assume that's rear end gears and not final drive ratio. The 20r head intake Ports are supposed to flow better at higher rpm but it would be difficult to fit to a later block, and with flat top/dished pistons it would result in a very low static compression ratio. The 20r has large, open, combustion chambers with little quench area. I feel the quench action and small chamber of the later style heads outweigh the advantage of the 20r ports. A combination of the two would be best... The 20r intake manifold is a single plane design which favors higher rpm output over the 22r dual plane design. Right now I'm running the stock diz And haven't noticed any issues but again I'm not spinning that high of rpm. A friend of mine has a 22r with a stock carb diz and will hit 7K on occasion without noticeable misfire. An upgraded aftermarket diz would no doubt be better than stock. While you are planning your build I would suggest doing some research on port cross sectional area and how it relates to engine output. It is information that was new to me and it's really eye opening seeing how physical limitations dictate peak torque/horsepower output and the rpm range in which they occur. I guess what I'm trying to say here is: focus on torque production rather than turning high rpm. Torque is directly related to combustion pressure and displacement. Displacement could mean the actual displacement of the engine but volumetric efficiencies of over 100% are attainable in a naturally aspirated engine. More torque throughout the entire operating range will produce more horsepower throughout the entire operating range. Are you allowed to run headers our do you have to run stock exhaust manifolds?