Datsun 510? race engine

[Jason H]

I have a 79 510 race car. I am going to be building a motor, While I use the current one.  

Our rules say Holley 350 carb (7448) and 2.5 litre max. I currently have a head and my engine is a L20B..  

I will be racing against Ford's and Chevy's primarily.. 

My question is. What would you guys do to make some real horsepower.  I see Schieder has a .625 lift camshaft.  Is it better to run longer rods or stroke it.  I see I can use a Z24 bottom end.maybe add the L20B head to it, aftermarket 4340 billet rods?  Does anyone know who makes a roller camshaft? Add big valves?  What is everyone's ideas. I want to beat these Ford's and Chevy's.  No turbos and ignition is a mad 6al.. 

[paradime]

Go to Rebello racing website and look at their parts list. Adding displacement isn't a function of simply using longer rods. "Stroking" the crank means the crank gives a longer throw of the rod and piston. Aside from a good quality header and free flowing intake manifold, HP on an L comes from head work; porting, bigger valves, and cam. A specific lift and duration should be matched with your needs, compression, carberation, high revving short crank or a low revving stroked, all of these things relate to what's the best cam lift and duration for your application. Z24 is a stout motor with big torque, but it's low revving. Throw enough money at an L20 and you'll get it to 2.3L and wind up to 9K rmp. With side drafts they're making 240hp, not sure what the Holly will do.

 

Do some research, you have a ways to go before these questions can really be answered

[datzenmike]

Using a Z22 crank and stock Z22 87mm pistons in an over bored L20B block (or the Z22 block) you can have a 2.2 liter

Substituting KA24E pistons and boring to 89mm you can have a 2.3

Or just switching to a Z24 engine you have 2.4 liters.

 

You are limited by the piston speeds as the stroke lengthens unless you want to go to exotic titanium rods and fasteners. But generally the red line is...

 

L20B 86mm stroke....... 7,000....8.5

Z22 92mm stroke......... 6,500... 9.84

Z24 96mm stroke......... 6,250... 9.47 compression with an open chamber U67 head. Higher if milled or block decked.

 

You can reliably hold up to these RPMs indefinitely. These are all stock rods and pistons and limited by their metallurgical properties. Higher than this and the rods begin to stretch from the g forces.

 

The best easy to find L head is the U67. Larger 280zx valves can be installed and it can be ported out. keep an eye out for a 219 or later issue V912 head. The most insane head would be the FIA but $6K-

 

Do you HAVE to use that Holly??? That's too bad. However you can probably remove the choke flap and cut away the entire choke area and smooth the incoming air path. grind down the throttle shafts at the butterflies to thin them. Can you make your own intakes?

 

Modify your oil pan with baffles and add extra volume to the sides to lower the oil away from the crank. Crank scraper/windage tray.

[Jason H]

Thank you. Car already has a good header and deepened oil pan.  I will be reusing those, once new motor is built..  

Yes, I am stuck with the Holley 350 carb.  

Current motor does have a camshaft and I am wanting to spin it 7,000 rpm..  

I will be buying new 4340 billet rods for new motor..  

Distributor and MSD box (digital 6al) will also be reused..  

The guy who wins alot, I helped unload his car at the Dyno shop and it dyno'd at 210 horsepower. So I believe the Datsun/Nissan combo I can achieve that horsepower or close to it..  

I am just trying to figure what Combo would get me to that horsepower range. 

[datzenmike]

What about the car itself? Have you removed all allowable excess weight? Weight to HP is the name of the game. So you don't need the heater or the radio.

[Stoffregen Motorsports]

I assume this is a circle track car...?

 

Do your rules say you need to run a stock type engine? Meaning, an L series based engine? Or just a displacement?

 

RPM's are going to be your friend in a circle track motor, but you will also need torque to get off the corners. Let's be clear here, you are talking about a "custom" engine build. My favorite hybrid L motor is the "2200" which is a long rod 89mm bore L20B stroke bottom end with an L head. This motor will rev to 8000 rpms easily making about 230 hp with dual 44's. With a Holley 2 bbl, probably about 215. It is a rev monster, but also makes good torque. Probably the best choice for you is going to be a "2300" which is a Z22 crank with long rods and custom 89mm pistons. They don't rev as high, but make a shit ton of torque. Either way, you're looking at custom forged pistons with a CR of about 12:1, which will require a big cam to use all that cylinder pressure, and a stable valvetrain that won't fall apart under pressure. Obviously, a race prepped crank, cam oiler, big valves, race prepped bearings, block, etc are recommended as well.

 

I worked for Rebello Racing for ten years, and I built a few strong circle track L motors while I was there. I would certainly give them a call and see what they suggest. If you're going to build the motor yourself, I might also source the pistons and cam from them (nobody does L motor development like Rebello). Either way, I would seriously consider having them build the cylinder head as they have two of the best L motor builders on the planet.

 

Cost for either motor? Roughly $5500 for a long block. Add a grand for dyno tuning. Build it yourself for about $3000. If you're racing for points, the extra $2500 to have them build it would be worth the investment.

[bananahamuck]

Have you raced circle track ever in your life? Or is this the first time?  

 

Is it 3/8ths or 1/2 mile? 

 

. 

Edited January 16, 2019 by bananahamuck

[datzenmike]

no.... I'm a virgin.

[Stoffregen Motorsports]

Never had the pleasure?

[G-Duax]

Sometimes seat time, and understanding chassis set up is worth more than HP.

[bananahamuck]

2 minutes ago, Stoffregen Motorsports said:

Never had the pleasure?

 

 

Meant for the OP 

 

.As i was thinking exactly what G-duax said in his post

 

 

And somehow mikes qoute slipped through my grasp 

 

.

Edited January 16, 2019 by bananahamuck

[Stoffregen Motorsports]

If this is a first race season, don't spend money on a motor. Spend it on testing and chassis setup. Nothing compares to seat time.

[Stoffregen Motorsports]

I will add that most Datsun circle track guys cheap out and take the easy route with little engine math or attention to detail. If you build a smart engine combo, tailored to your driving style, you will be ahead of the curve from the drop of the green flag.

[Jason H]

1 hour ago, bananahamuck said:

Have you raced circle track ever in your life? Or is this the first time?  

 

Is it 3/8ths or 1/2 mile? 

 

. 

It is a 1/4 mile dirt track. I raced Ford's. Made conversion to Datsun.

[Jason H]

1 hour ago, G-Duax said:

Sometimes seat time, and understanding chassis set up is worth more than HP.

Car has been raced before and has won again St the Ford's. Set up wise, Car handles good, just a little loose. Which I will check springs and scale car. Car has to weight 2100 lbs. With driver.  All extra weight has been removed to the point the car is 120 lbs. Light with driver. 

[Jason H]

1 hour ago, Stoffregen Motorsports said:

I will add that most Datsun circle track guys cheap out and take the easy route with little engine math or attention to detail. If you build a smart engine combo, tailored to your driving style, you will be ahead of the curve from the drop of the green flag.

I understand, car currently has motor and race ready. I want to build a bigger replacement motor.  I always go all out on my motor builds. Always, good rods, balancing, etc.  Spend a few hundred now, or replace motor sooner.

I am trying to get ideas on back up motor..

[Jason H]

1 hour ago, Stoffregen Motorsports said:

If this is a first race season, don't spend money on a motor. Spend it on testing and chassis setup. Nothing compares to seat time.

Car is pretty competitive with motor now. Has actually won...  I like to build as big motors as I can. Big valves and porting and polishing is ok. Up to 2600ccs. Even allowed Roller Solid Camshafts. Just like 200 lbs. Compression rule.

[paradime]

Barona I'm guessing. Opened 5 years after I left SD, so I've never seen it. I spent a lot of time at Speedway 117 Otay Mesa, Del Mar, El Cajon, and Carlsbad back in the day. All of them gone now. Damn glad you guys are carrying on the good fight. Doing it in a dime... Oh Hell Yeah. 

 

I raced 125cc motocross at 117 and Carlsbad, and autocrossed my 510 at Jack Murphy back in the early 80s. Best time of my life. 

[G-Duax]

Roller rockers are not really a viable option for the L-series head.

One place in Australia makes them, but they are expensive, heavy, and due to the roller having a much smaller radius than the stock style rockers, really screw up the cam geometry.

[paradime]

I don't think there is such a thing as an overhead roller cam. On a roller rocker the small roller is what makes contact over the top of the valve stem and shouldn't affect cam geometry at all. It eliminates side load on the stem and reduces wear.

[Stoffregen Motorsports]

8 hours ago, Jason H said:

Car is pretty competitive with motor now. Has actually won...  I like to build as big motors as I can. Big valves and porting and polishing is ok. Up to 2600ccs. Even allowed Roller Solid Camshafts. Just like 200 lbs. Compression rule.

I've heard of guys building 2500cc L motors, but I've never built one. A stroked and bored Z24 bottom end with an L head would be pretty torquey, but I bet it wouldn't rev at all. The full race KA24E motors I built in the 90's for SCCA GT3 racing only revved to about 7200. You would definitely want to weld on extra crank counterweights and knife edge the crank, as well as having it nitrided, cryo treated, metal-laxed, etc. The combustion chambers would have to be opened up quite a bit for proper squish.

 

Since I've never dirt raced a 510, I wonder... does having adjustable toe in the rear help with turn in? A bit of trailing throttle oversteer could be the ticket in the dirt.

[datzenmike]

The KA is the same stroke as the Z24 so 6,250 it tops unless using exotic parts to keep it together. If limited to an L head then easier to use a Z24 block. The KA-E pistons will fit the Z24 rods if going higher compression and the 240sx pistons are fully floating.

[Jason H]

1 hour ago, Stoffregen Motorsports said:

I've heard of guys building 2500cc L motors, but I've never built one. A stroked and bored Z24 bottom end with an L head would be pretty torquey, but I bet it wouldn't rev at all. The full race KA24E motors I built in the 90's for SCCA GT3 racing only revved to about 7200. You would definitely want to weld on extra crank counterweights and knife edge the crank, as well as having it nitrided, cryo treated, metal-laxed, etc. The combustion chambers would have to be opened up quite a bit for proper squish.

 

Since I've never dirt raced a 510, I wonder... does having adjustable toe in the rear help with turn in? A bit of trailing throttle oversteer could be the ticket in the dirt.

Here is the car racing.  I am going to put a little more caster in right rear. To get better grip and tighten the car up a little. 

[Jason H]

8 hours ago, paradime said:

Barona I'm guessing. Opened 5 years after I left SD, so I've never seen it. I spent a lot of time at Speedway 117 Otay Mesa, Del Mar, El Cajon, and Carlsbad back in the day. All of them gone now. Damn glad you guys are carrying on the good fight. Doing it in a dime... Oh Hell Yeah. 

 

I raced 125cc motocross at 117 and Carlsbad, and autocrossed my 510 at Jack Murphy back in the early 80s. Best time of my life. 

Yes, Barona. Car has been around. I think I am the 3rd owner.  Car just lacks a little power. 

My Family raced at Speedway 117 and I spent 30 years working on cars at Cajon.  Miss both tracks. I still ajng out with the drivers once in a while.. 

Boy, the memories....

[paradime]

3 hours ago, Jason H said:

Here is the car racing.  I am going to put a little more caster in right rear. To get better grip and tighten the car up a little. 

 

With the 510's trailing arm rear suspension it's very different from the Fords. When you say change caster a bit, are you talking from the top hat, or extending the trailing arm?  Did you mean camber? I think what Suffergen was talking about by adding toe is Byron and Datsport (AU) both make adjustable rear trailing arm brackets that enable toe and camber adjustments. Although I know the 510's suspension very well, by no means do I profess to know anything about flat track car suspension setups. There was a group of guys here who converted a flat track 510 into a budget enduro car. When they tore it down, here's what the found:

 

The front right had multiple springs and strange spacers. 

  The left rear spring was about half the height of the right rear spring.

  The right rear shock was adjustable, and the rod cover was removed.

  One of the front struts (I'm thinking the right front) had the top hat modified for camber and/or caster.

https://ratsun.net/topic/73011-swamp-thing-jbc-enduro-car/?do=findComment&comment=1532000

 

There was also a response from someone saying:

 

left rear lowest ,, right front highest to counter the dive as you hit brakes and go into corner.  if you go out to short track you will also notice every tire is a different size and tire pressure also..

   that's why there is also a rule how much camber the right front can have cuz guys will extend lower control arm and try to almost lay the right front tire parallel to the ground if there wasn't.

 

Hope this helps.