Project: Building a SR20DET Head to rev 9000K+ [PICS HEAVY]

[ILikeMy240sx]

you can email me if you want.

[welddrft]

NVM I think I figured it out. I went up at least 3 or 4 sizes on my mains and wondered why the plastigage size looked the same as the stock bearing grades. So I slapped in my Nismo Heavy Duty bolts torqued em down and finally, the correct readings!! Thought I was doin something wrong at first, but I guess the stock main cap bolts were poo and weren't holding torque.

[thang nguyen]

I was wondering that if tomei test kit contains 8 shims and 8 guides, 4 for in take a 4 for exhaust for both shims and guides, which side of the rocker arms do the shims and guides go? I just can't seem to visualize how they are installed:

valve/shim/guide/rocker/cam

or some other way.

because there are 2 valves per cylinder, so is it one guide and one shim per cylinder for intake and exhause.

please clarify because I have going on the route, just need to order lifters.

Thanks.

[ILikeMy240sx]

Just got back from the machine shop. They will cut the rocker arm for me. YAY! I will take some pictures when I get them back in few days.

As for shims and guides, the machine shop can't shave down anything that small. So Im just going to order from RHDJapan. They told me 98 dollars shipped for all guides and shims I need which I dont think is that bad.

RHD Japan FTW.

Thang,

To answer your question. The guide (slot in the middle) goes on the left leg of the rocker arm. The shim goes on the right leg of the rocker arm.

So, each rocker arm needs 1 guide and 1 shim. So in total, either intake or exhaust side will have 4 guides and 4 shims. Now, in the entire head there will be 8 guides and 8 shims.

Honestly, if you are still figuring out the difference between guides and shims and where things go maybe solid lifters are not for you. I really dont want people to buy this thing and install it without knowing anything and end up breaking things....

[thang nguyen]

I had an idea, but after reading all the posts and looking at the diagrams, I got disoriented and scrambled it all up. Thanks for clearing it up, Oh are you porting the head also? To rev so high, doesn't the head need some porting to allow for a better flow of intake air?

[Tuning Factory]

damn... great write up. all i have to say. hahaha

[DrifterProdigy85]

Was wondering why your going BC Hydraulic cams instead of HKS/Tomei/Jun Solid cams? I know hydraulic cams can be used but wouldnt more power be had from Solid cams because of the more aggressive cam lobe ramping?

[karmakaze]

I had an idea, but after reading all the posts and looking at the diagrams, I got disoriented and scrambled it all up. Thanks for clearing it up, Oh are you porting the head also? To rev so high, doesn't the head need some porting to allow for a better flow of intake air?

no. the head design of an sr is pretty good to begin with. a p&p will only bring minimal gains.

[ILikeMy240sx]

Was wondering why your going BC Hydraulic cams instead of HKS/Tomei/Jun Solid cams? I know hydraulic cams can be used but wouldnt more power be had from Solid cams because of the more aggressive cam lobe ramping?

See below...
Modified by ILikeMy240sx at 1:43 PM 2/6/2007

[ILikeMy240sx]

Guess what....

Im chaging cams. Damn it. I really didnt want to change cams as this will require me to measure all my clearances agin (*sigh*)... damn.

But anyways, Ive given it ALOT of thought and you know what... I am going to go with solid lifter Cams from Tomei.
Modified by ILikeMy240sx at 11:45 PM 2/7/2007

[S13FASTBACKSR]

can i ask why you are changing?

[ILikeMy240sx]

I thought about it alot before I went to bed.

Knowing me, Im going to want more power. Im really greedy when it comes to power. Watch, if I were to put on those stage 2 cams, few months later I am going to want more power and upgrade cams and turbo anyways....

So, Id rather drop in everything now and not worry about it later.

[S13FASTBACKSR]

lol i feel you man..im the saaame way I love that power..im power hungry..well what size are you going with from tomei? you were going with 272's correct? the next size up from that (in tomei sizes is 280s) BC also makes a 280 from what i was told..what will 280's and the .86 look like together throughout the powerband

[nonvtecaccord]

no you will still have to do it but I doubt that after the first 5000 miles or so, you have to change out many shims.

You will probably need to replace one or two but not many every 5000 miles after the first 5000 miles.

I know for fact that they need to be adjusted because GTI-R motors are notorious for making tappeting noise due to people not adjusting shims. They have solid lifters so thats one of the things they have to keep in check.

BTW, I just finished translating that Tomei manual... Just gotta put it into PDF now.

Wait, so solid lifters need reshimmed every 5k miles? I think I will stick with my HL's for street use.

[S13FASTBACKSR]

Wait, so solid lifters need reshimmed every 5k miles?

yes approxiamately

[nonvtecaccord]

If my car was going to be a race car, I would think about solid lifters. Solid lifters don't seem very "streetable". Perhaps streetable is the wrong word, but I perfer as little general maintance as possible.

[ILikeMy240sx]

lol i feel you man..im the saaame way I love that power..im power hungry..well what size are you going with from tomei? you were going with 272's correct? the next size up from that (in tomei sizes is 280s) BC also makes a 280 from what i was told..what will 280's and the .86 look like together throughout the powerband

Probably 270s... I dont want my powerband shifted too much to the right.

[S13FASTBACKSR]

so your going with a bit smaller cam because with the .86 and 272's you will be producing lots of power in the top end and not nearly as much in the low to mid range...so therefore you want to even it out and thats why you are going with 270's?

[karmakaze]

Probably 270s... I dont want my powerband shifted too much to the right.

not going to stagger?

[S13FASTBACKSR]

karmakaze what do you think the best staggered setup would be with that turbo..264/272? do you always prefer staggered over the same size cams with any turbo?

[karmakaze]

karmakaze what do you think the best staggered setup would be with that turbo..264/272? do you always prefer staggered over the same size cams with any turbo?

in my old setup, i had HKS 256in 264out step 1 cams and loved it. In the setup I am putting together now I have 264in 272out step 2 cams.

once you upgrade to a turbo that flows enough to justify high duration cams you can tweak your powerband to your personal peferance by selecting the appropriate cam duration and/or staggering.

staggering just gives you a little bit of 2 worlds.

256/256 focus is on low end256/264 lots of low end a little bit more top 264/264 good low end ok top end264/272 good low end bit more top end272/272 focus is on top end

[S13FASTBACKSR]

256/264 step 1 with one turbo? i am a bit confused with something though if you dont mind answering..why does a high duration cam say 272 "overkill" a small turbo say a t28..wouldnt it just make for power all throughout the powerband..the t28 spools and boosts in low to mid rpms and then it starts dying out around higher rpms..but the 272's have already kicked in a little before the t28 dies out which causes for top end power..why is that wrong? this has been boggling my mind forever now

[karmakaze]

256/264 step 1 with one turbo? i am a bit confused with something though if you dont mind answering..why does a high duration cam say 272 "overkill" a small turbo say a t28..wouldnt it just make for power all throughout the powerband..the t28 spools and boosts in low to mid rpms and then it starts dying out around higher rpms..but the 272's have already kicked in a little before the t28 dies out which causes for top end power..why is that wrong? this has been boggling my mind forever now

think of it like this, your engine is a air pump. it flows so many lbs of air per minute and this number varies based on RPM. Theoretically speaking, (disclaimer: these are all made up numbers! i did no real math or research) lets assume that an engines cams allow for a max flows of 25lbs per minute @7000RPM and you are running a small t28 that puts out 20lbs per minute @7000RPM. Lets say that @ 6500 your engine is pumping air at 20lbs per min. this mean that above 6500 your not going to be gaining anything except for damage to your turbo by being out of its effenciency range. lets say you throw some bad *** cams in that flow 45lbs per min. This changes the "range" of your flow. so instead of having a range of 0-25lbs that corresponds to your RPM of 0-7000 you have a range of 0-45lbs in that same 0-7000 RPM range. If you plot this on a graph you will see that the engine will now be able to flow that 20lbs at like 4000RPM (thats a guess) so you will not really see any gains above that.

I think thats right. Someone doublecheck to make sure my logic is working today.

[S13FASTBACKSR]

lets assume that an engines cams allow for a max flows of 25lbs per minute @7000RPM and you are running a small t28 that puts out 20lbs per minute @7000RPM. Lets say that @ 6500 your engine is pumping air at 20lbs per min. this mean that above 6500 your not going to be gaining anything except for damage to your turbo by being out of its effenciency range.

Idk man..above 6500rpms your not gaining anything accept turbo damage b/c the the turbo is out of its efficency range? 25lbs per min cams and a 20lbs per min turbo at a 500krpm difference sounds like a close enough efficiency range to me lol ..how close do you have to be?!?! idk though im sure im looking at it wrong

[karmakaze]

Idk man..above 6500rpms your not gaining anything accept turbo damage b/c the the turbo is out of its efficency range? 25lbs per min cams and a 20lbs per min turbo at a 500krpm difference sounds like a close enough efficiency range to me lol ..how close do you have to be?!?! idk though im sure im looking at it wrong

Those are not real numbers. I was just using it as an example. that 500RPM may not make any difference. but that little bit was irrelivent to the point i was trying to make. Maybe someone else will chip in and explain it better, or correct me.

[ILikeMy240sx]

Ok going with higher duration cams enables your motor to have more flowing capabilities at higher RPM. However, you do lose some torque produced in low to mid range. This is why going with higher duration cams has the effect of shifting your torque curve to the right of the dyno graph if you will.

Obviously, going with ridiculously high duration cams when your turbo can't match to flow enough air is pointless since your gain up top will be minimal AND you will lose torque your low-to mid range.

You really want to think about the kind of turbo you will run and then go with properly sized cams for that.

For me, I see GT30 in the future and I want to get cams to match that but I really dont want to shift my torque curve too much to the right. Yes, it will give me more power up top but at the cost of losing torque your low to mid range.

I am kind of curious as to how the 270s Im planning to get will do with the .64AR GT2871R that I have. With Tomei cams, I cant stagger 260 and 270 beacse 260s have less lift (12.00) than 270s and 280s (12.5). Since I do not want to put 280s, I am going to stick with 270s.

[S13FASTBACKSR]

I think it finally hit me..Say you have a small turbo..a t28 and you put on 270's or 272's or 280's..those high durations flow a loooooot of air..like karmakaze said x amount of lbs/minute..those cams flow a high # of lbs/min..and that turbo flows a small amount of lbs/minute..The reason you must match your cams with your turbo is because when all of that air that the cams are letting in get to that turbo its like hitting a brick wall ( well the flow does not stop completey but it slows down extremely if you will)..and if you put a huge turbo on and small duration cams its not enough air to match what the turbo desires so you are being robbed of power both ways..am i correct?

[ILikeMy240sx]

Got my rocker arms back from the machine shop.

They tried with a mill and couldnt do it so they did it with a grindstone instead.

Total cost $45 for all 8 rocker arms.



Oh and I placed an order for Tomei Solid 270s god I cant wait to get those.

[DrifterProdigy85]

270's will be perfect for the 2871R .86. The cams will have power kick in hard as soon as full boost is hit. Ill be going with BC 272 Race Cams with mine.

[C - ROD]

Got my rocker arms back from the machine shop.

They tried with a mill and couldnt do it so they did it with a grindstone instead.

Total cost $45 for all 8 rocker arms.



Oh and I placed an order for Tomei Solid 270s god I cant wait to get those.

is that all, they hardly took anything off huh?