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

[C - ROD]

i might be interested in the camshafts if they are still around when i get paid next week

[ILikeMy240sx]

is that all, they hardly took anything off huh?

Nope, not much at all. If you look at the manual, it says to cut about .5mm wide and 2~3mm long so its just getting rid of the tip of the legs of the rocker arm so that they don't dig into the shims with 12.5mm lift and solid lifters.

[ILikeMy240sx]

I just got an email from RHDJapan... These cams are on back order until 3/14.

So I called FRSport and bought the last set they had in stock. WOOOOOT!!!!!!!

[S13FASTBACKSR]

congrats man..im waitin for rhdjapan to send my solid lifters out ..hopefully i dont have to wait as long as you did lol

[TchouikoS13]

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.

Alright, i read this over like 7 times and im still not quite sure if i get it. (Sticking with previous scenario) If you get those bad *** cams your basicly allowing more air into the engine, shifting your graph to the left (lower rpms), and hitting the turbo's max it the lower rpms (20lbs @ 4000rpm) which in some senses is good(if u want it that is). Was i in the ballpark at all on that one?

[S13FASTBACKSR]

no..the bigger the camshaft the more top end you have..the smaller the camshaft the more bottem end you have..if you have a t28..then 256 are perfect and you will have a nice #'s on the left side of the graph..you will have full boost at about 3krpm or so and will hold to about 7krpm..the bigger the turbo you have, the more top end you have because of the lag..same with the bigger cams its like lag..now this is how having a small turbo with small cams works better than a small turbo with big cams..visa versa for a big turbo with small cams versus a big turbo with big cams ...see if you understand it better

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

[cheapscheisst]

this summer i plan on going top mount GT30. i don't want to deal with the maintenance issues associated with solid lifter, so i'm leaning towards a set of tomei 270 lash cams and valve springs. is this a good choice? also, with rocker arm stoppers, how high could i safely rev?

[S13FASTBACKSR]

270s are too big for the gt30 imo..i would go with hks 264 step 2's..also i was talking to a guy who had a 500+whp sr and he is totally against ras..he has had first hand experience with different brands of them for the sr and he told me that without ras you will throw rocker pads at certain rpms but they do not break they just fall in the head somewhere..with ras they will still come off and not only do they come off..the ras breaks them into many many pieces
Modified by S13FASTBACKSR at 7:06 PM 2/11/2007

[cheapscheisst]

so with hks step 2 264s, at what rpm does throwing a rocker pad become a hazard?

[cheapscheisst]

also, are you sure that 270s are overkill for a 450+whp sr?

[S13FASTBACKSR]

imo 270 or 272 are a bit too much for the gt30 maybe somebody else would disagree..why dont you just step the turbo up a couple of notchs? gt35r external wastegated..272's then ftw..by the way on hla its safe to rev to 8krpm maybe just a liiiittle bit more then you might start throwing rocker pads

[sl87]

Just wanted to say VERY nice write up...it took me an hour to read everything. Keep it coming.

[thang nguyen]

Say hypothetically, that you are running very high cams such as HKS step 3 or Crower race cams. And hypothetically, that you ahve solid lifters to rev to 9K RPMs. Then what would be an appropriate turbo for this set up, either for a stock bottom end or a forged internal bottom end. How much power could one expect from a setup as such.

[S13FASTBACKSR]

this is exactly what i have been thinking about for the past week..after my solid lifters and high duration cams i am going to go with a nice size turbo that can put out 500hp while im still on the stock block..i was looking into the SC61 or the gt35r..i think these would be appropriate turbos for this goal..i havent had much time to look around much so if i find anymore i'll let you know

[cheapscheisst]

k thanks for the advice. i can get a much better deal on tomei 270s w/adjustable cam gears than with the HKS 272s. which would you suggest?
Modified by cheapscheisst at 5:31 PM 2/12/2007

[ILikeMy240sx]

also, are you sure that 270s are overkill for a 450+whp sr?

270s are definitely not an overkill for anything over 400 RWHP cars. Most of the dynos Ive seen with that much power have 270s or higher. Even with GT2871R .86 ex A/R, the boost should come on pretty strong and pull hard all the way to red line. Flowing up top is so important especially when you are increasing your rev range by going solid lifters so I wouldnt call 270s an overkill.

I am interested in how my GT2871r 52 trim with .64 A/R will do with the cams Im getting. I do have the dyno data saved on the Mustang dyno so once I get everything in and break in the cams, I am going to put it on the dyno to see what the torque curve looks like and compare that to when I had stock cams.

[cheapscheisst]

actually i decided to stick with lash cams because i want to avoid the maintenance hassled associated with them. i'll have enough to deal with if i'm pushing 500+whp.

[S13FASTBACKSR]

yes it is very important to make power above 8krpm with solid lifters because otherwise you wouldnt need them..but he is not going with solid lifters due to the maintenence of the shims..therefore 264's will be good..i know a guy who lives in my town with hks 264's step 2's and a 35r on hla making over 500hp so 264's are definately not underkill for the setup you want..especially if you are going to go with a gt30 i think 264's would be better than the 270's or 272's imo..they make power quicker and will hold to 8krpm and imo are the perfect size for the gt30

[cheapscheisst]

i've already decided to fork up the extra $100 for the gt35 version of the hybridynamics top mount kit. therefore i thought it would be more beneficial to go with the 270's

[S13FASTBACKSR]

gt35r with 270's or 272's on hydraulic or solid lifters ftw but...gt30 with 264s on hydraulic lifters ftw

[Dugi]

I am also building my SR. I have the GT3076R and BC 264 cams and all the supporting mods. excited to see the outcome of this setting. I had a GT2871R with bon stock block and ran 11.73 sec 1/4mile on slicks. really want to see how I ran with fully built motor, GT3076R and cams.

[Mistaken]

Very nice work, and great write up. I had a quick question for you though, sorry to go off topic, but what cams would you suggest for someone running a gt2871r .86 a/r, 3 inch exhaust, tubular header, injectors, e-manage,fmic, and all the other supporting mods? My project goal is around 450rwhp and i don't plan to rev it past 8k or so and i won't have the ability to reshim everything every 5000 miles when I'm away at college.

Thanks in advance for the help.

[DrifterProdigy85]

Id definitly use the BC 264's with the GT30R. There 264 Duration and 12.05mm Lift. The duration of the cams seem to have more effect on when power is being delivered. The lift seems to determine how much power is being delivered. Looking at it this way means you can have 2 sets of cams with 264 duration but the set with higher lift will allow more power to be made.

[ILikeMy240sx]

LoL... I cant believe you guys are talking of HLAs in this thread haha.

Solid lifters FTW....

HLA + Big lift cams -> collapsed HLA -> fishing in your head for pieces of rocker arms. No good.

I dont know... Failed lifters suck even if you have to check and re-shim solid lifters regularly. Id rather do that 10 billion times than see bits of rocker arms everywhere and my cams get ruined.

But then again... it all comes down to you in the end. I can sit here and lecture about lifters all day long but if re-shimming is not your cup of tea then thats how it is.

[S13FASTBACKSR]

i love solid lifters

[ILikeMy240sx]

Tomei 270s solids are on their way... WOOOOOTTT!!!

[S13FASTBACKSR]

congrats bro...my tomei solid lifters are taking forever to be shipped

[jubee]

any more updates on this build?

[ILikeMy240sx]

Actually I get my solid cams tomorrow from UPS. I will upload pics when I get them tomorrow.

I have an exam in my Finite Element Analysis class on Wednesday so after that farking exam, I am going to start measuring my clearances again.

[S13FASTBACKSR]

well my friend whenever you are done with the test shims i will send you the money for them just let me know