Type 4 rallycross engine.

[Ebjørkli]

I`m buliding myself a new type 4 rallycross engine this winther, with 71mm crankshaft and 103mm bore. I`m planning on using 48 or 50mm Jenvey TB`s and DTA S40 ecu, with E85 as fuel.
With the heads I got I can eighter use 48mm or 50mm intakevalves and 40mm exhaustvalves, 11,0- 11,5 compression ratio with 1mm deckheight. At this time I got a 316 P-cam, but are not sure about this choise. The heads are also equipped with 1,48 Pauter roller rocker arms. I`m planning on using B.A.S. Ahnendorp`s header.

So here the questions:

What is recommended? 48 or 50mm TB`s? 48 or 50mm intakevalves? Witch cam shuld I use with E85 fuel?
Is it ok to adjust deckheight with coppergaskets in the heads?

I need this engine to be strong and hi output power and torqe type, durability is not what I need...
Driveability would be great, buty not a necessity.

Thanks in advance, hope some of you guys can answer me, so I can order my parts soon...

[dstar5000]

78mm crank for torque, small stroke and big cyls isn't the way to go.
78X103=2600cc
55cc heads and 1mm deck =11.3CR

50mm TBs sound nice, but the 320 would be a better cam fro that CR...

Adjust CR with barrel spacers ONLY, keep your deck height to 1-1.5mm.

Over that and it will make it hard to tune.

Don

[Ebjørkli]

Thanks for the answer!
My problem is that I compete in a class that says max 2400ccm, so I cant go for a 78 mm crankshaft with the cylinders I got... It`s the cam, valvesizes and TB`s that are my maine questions, and I just got a good answer about it

[Type 4 Unleashed]

Hi again Ebjørkli

I can give some info on the cam, it's the Eurorace "P" cam, .410 lobe lift, 280* dur @ .050 more than likely 106* lobe centers, it's has about a 4,000 to 7500 power range, depending on your gearing and what rpm you intend to run in, it may be an option for you. Compression ratio 11.5 to 12.0 with this cam.

But the rocker ratio could be an issue, the .410" lobe lift and the stock 1.3 ratio rockers give you .533" valve lift, but the Pauter 1.48 ratio rockers will give you .607" valve lift. And if your heads will flow at .600" valve lift then they could be option.

Valve sizes ? I remember you saying a while ago you would be doing your own heads. If you are not going to be having some extensive welding done to the int ports in order to get some nice size ports, then I think it would be a waste to go a 48 or 50mm intake valve on a basically stock reworked int port, the valves could flow but are restricted by the much smaller int port. I think a reworked stock port will support a 46mm int valve and a good valve pair would be 46 x 40.

I don't know what you intend to use for valve seats, but would suggest you make some for example in say an outer diameter that would be needed for say 54mm int valve, but the inside dia for the 46mm int valve and the same principal for the exh seats, but you would have to figure out what you could get to fit. Now what this does is provides a wider seat foot print in the head which holds up far better to increased spring pressures required in running constantly in the upper rpm ranges.

The Exhaust ? You are going to need a big exh at least a 1 3/4", everything else will be a waste if you choke the motor with a small exhaust.

[Ebjørkli]

I ended up buying GetBackOnTrack`s haeds for his 2840ccm race-engine, they seemed like great heads for my application:
http://shoptalkforums.com/viewtopic.php ... 3&start=75
With these heads I can get larger inletports I think, but I haven`t figured out the design yet.

The BAS Ahnendorp header is 39mm inside dim, I think it looks a bit to small, but It`s wat I got for now...

[Wally]

I
The BAS Ahnendorp header is 39mm inside dim, I think it looks a bit to small, but It`s wat I got for now...

Those have reportedly supported over 200 hp from a 2366cc even with both dampers...
That header is ~perfect imo for a 2366cc.
I am with Richard on the valve sizes: I ran 46x40 on original heads with the same 5.3" valvelift and got 220hp from it (although from 300cc's more) with 48mm Jenvey's. They flow more than enough. Bigger TB's only give a less lineair throttle respons if you know what I mean by that.

Good luck on the build!

[Ebjørkli]

Sorry I have not updated this thread, but I have not dismantled the engine yet. Right now I'm working on welding up the car, with new channels and various reinforcements, including a removable rear section.
I will be back to the engine-work soon, when the goal is to be done with all the welding before Christmas

Thanks for all the answers, I take all the help I can get, I`m a rookie at this!

[Ebjørkli]

Then it seems that I can get something done with my engine this weekend! Sitting here and ordering new valves, dual springs, retainers, keepers, and a new set Pauter rockers. What`s the best, bushed or roller bearings? And I was wondering, Is the 499.99 price at EMW for the rockers per head, or for both heads?

However, Type 4 Unleashed, you mentioned that my P cam and Pauter rockers maybe was a problem? Have run 2 seasons with it now, and it has gone well. Is it the flow that`s the problem? You see, I do not have much experience with flowing and such, so I am very grateful for all the help! Do you guys recommend another cam to flow better?

My plan is to order everything from EMW, I have good experience with them before, great service!
Fast shipping, and really good candy!;)

[Type 4 Unleashed]

Then it seems that I can get something done with my engine this weekend! Sitting here and ordering new valves, dual springs, retainers, keepers, and a new set Pauter rockers. What`s the best, bushed or roller bearings? And I was wondering, Is the 499.99 price at EMW for the rockers per head, or for both heads?

However, Type 4 Unleashed, you mentioned that my P cam and Pauter rockers maybe was a problem? Have run 2 seasons with it now, and it has gone well. Is it the flow that`s the problem? You see, I do not have much experience with flowing and such, so I am very grateful for all the help! Do you guys recommend another cam to flow better?

My plan is to order everything from EMW, I have good experience with them before, great service!
Fast shipping, and really good candy!;)

Hi Ebjørkli

Order the Bushed rockers, and the $499.00 price is for both heads.

The problem with the "P" cam and Pauter rockers is they will give .607" valve lift, where before with stock 1.3 rockers valve lift was .533" lift. The Problem is getting your heads set up correctly to handle the increased valve lift.

Now I guess you are going to run the heads you bought from GetBackOnTrack ? And they could very well flow at .600" valve lift.

Jorge has some springs that will handle .600" valve lift, and I actually have some that will handle .700" valve lift...

And both sets of springs can be set up at anywheres from 1.510" to 1.550" installed height, where the stock spring installed height I believe has been said to be 1.510", so these will be very easy to set up.

But what has to be looked out for is sufficient clearance between the bottom of the retainer and the top of the valve guide at full valve lift. I would like to see a bare minimum of .125" between the top of the guide & the bottom of the retainer. And for reference I like to see at least .100" before coil bind on the valve springs.

Then rocker geometry will have to be checked then set you will probably have to cut new push rods, and I would think about a set of dual tapered ones would be a good choice.
Then you will need to check valve to piston clearance, which could also be an issue

Now your saying you have ran the "P" cam for 2 seasons ? Does it work in the RPM range you run, and are you happy with it ? Some better flowing heads and a good exhaust could very well improve it's performance ?

These clearance spec's are what work for me for longevity on the street, other people may use something different.

For example a lot of people like to run their valve springs @ .050" before coil bind for the extra pressure which causes the springs to heat up more and lose their pressure faster running so close to coil bind, which I believe to be a big big mistake, when they can choose a different spring for the added pressure they want and then have plenty of room before coil bind thus extending spring running life a whole lot more than before, for you, use what you feel comfortable with.

[Ebjørkli]

Thanks, now I understood perfectly what you ment about flow! I just wrote a long answer here, but suddenly I hit one button, and it dissapeared! I don`t like that,hehe

I just sent Jorge at EMW an email with my question regarding the dual valve springs, hope to get his answer soon, so I can place my order;) Looking foreward to get this package in the mail! Is it so that you work over there at EMW to Richard? Just curious, maybe I could place my order with you? Maybe you could get me those .700" lift springs;) But for now, lets see what Jorge answers...

I`m really happy with how my cam works, it`s just about perfect for my dogbox gear-ratios, I change gear in about 7800 rpm,
and then I hit the new gear just perfect. Really good driveability with my combination. But, everything can always get better,
with encreased power!! My dogbox can always handle it, it won`t break.

About the roller rockers, now I use the ones with bearings, and If I order the bushed ones, can I still use my old ones as spares?
Can I use them If one of the bushed ones break? Just good to know, not necessery to sit here with a good set of roller rockers that I can`t use:) In case they aren`t interchangable, are the bushed ones much better?

Ok, now I need to go out to the workshop and start tearing down the engine, looking foreward to it!! Again, thanks for all the help,
I need it!!:D

[Ebjørkli]

By the way, is this drysump pump a good option? This pump needs to get oil from both dry sump tank and thru the oil pickup tube?
I thought one of the points with a dry sump pump was that I didn`t need any oil from the oil pickup tube, hmm...
I do a lot of hard cornering. Any good ideas, I guess there are plenty experience about this around here;)

[Type 4 Unleashed]

Thanks, now I understood perfectly what you ment about flow! I just wrote a long answer here, but suddenly I hit one button, and it dissapeared! I don`t like that,hehe

I just sent Jorge at EMW an email with my question regarding the dual valve springs, hope to get his answer soon, so I can place my order;) Looking foreward to get this package in the mail! Is it so that you work over there at EMW to Richard? Just curious, maybe I could place my order with you? Maybe you could get me those .700" lift springs;) But for now, lets see what Jorge answers...

I`m really happy with how my cam works, it`s just about perfect for my dogbox gear-ratios, I change gear in about 7800 rpm,
and then I hit the new gear just perfect. Really good drive ability with my combination. But, everything can always get better,
with increased power!! My dogbox can always handle it, it won`t break.

About the roller rockers, now I use the ones with bearings, and If I order the bushed ones, can I still use my old ones as spares?
Can I use them If one of the bushed ones break? Just good to know, not necessary to sit here with a good set of roller rockers that I can`t use:) In case they aren`t interchangeable, are the bushed ones much better?

Ok, now I need to go out to the workshop and start tearing down the engine, looking forward to it!! Again, thanks for all the help,
I need it!!:D

I agree it sucks, in the middle of writing a response you miss key and wipes it out, a trick I have found if you do previews along the way of what you are writing if you miss key then you can go back a page then refresh that page and it at least brings it back to the last preview, so you don't loose everything.

No, I don't work there just hang out when I am not working. As too the springs, the ones I have I wouldn't recommend them for your cam, it can't use them. So you are already running Pauter rockers on the "P" cam, what heads & exhaust were you running before and which springs were you running also ? I take it the BAS Ahnendorp header you got now is bigger than what you were running before, and if that is the case then your other exhaust was choking your motor, so with new bigger heads and a bigger exhaust, you will see a noticeable difference. I will say I would like to see a 44.45mm outer diameter header and I believe your motor would also. The 39mm i.d. pipes I think will choke your new heads like your old exhaust did on your old heads.

As for the rockers, everyone has been ordering the bushed ones, so he usually keeps them in stock, so those would be available, roller ones would have to be ordered. I would like to see replacment rockers to be the same so if you have roller than go with roller, no price difference.

I gather your on a budget, but have you thought about a backup motor ?

[Steve Arndt]

What about Jake saying the new rockers with bushings and through oiling break and are no good? Has anybody else used them yet?

[Getbackontrack]

Hi Erling.. The Idea with the drypump pump is that it sucks oil right into the oil galleys from the extern oil tank, then the oil gets sucked back up to the tank from the sump through the original pickup... If the original pickup wasnt there, all the oil from you tank would end up in the sump in your motor.

Regards, Jakob

[Steve Arndt]

With a 2 stage pump, one stage, nearest the case, sucks through the stock case pickup and dumps into the external tank. The second stage pulls from the tank and supplies the pressure/volume for the engine.

With a 3 or 4 stage they simply add more suction/scavenge stages to pull from various areas.

s