Planning my new build
 

So a few of you have seen the pics in the BS thread about my see through block/oilpan.

Well I dont know if the head had has been damaged, but hopefully not.

I am going to build a pretty serious engine this time around.

My goal is about 300whp and 270ftlbs. Fully boosted about 3200rpm.

I need more mid range balls than super top end power.

I plan to run better valve springs though, so I am looking to rev to 8000-85000rpm.

I am also wondering what you all think about the CR I should run. I am thinking 9.5:1 to help with low end and spool..

If you would please give me your .o2 in regard to this build and where to source the parts at obviously the lowest price.

FYI- My machinist is great. He is into the JE product line.

Help:
What head gasket
Oil pump
valve spring kit
ARP hardware- Head bolts, Main cap studs
Valves?? Go over sized? in take and exh?
Pistons
Rods


Thanks everyone. I will be taking my time and saving for this one..

-Jeff

Hmm. This is a race car basically, right? Any street time? No idea about prices and where to buy, but here's my opinion on the matter anyways.

Studs are not needed. You can buy them, but they aren't needed. Point of studs is to allow you to put extra torque on the part you're putting the studs on and reduce surface defection on the part it goes into. IE, put 100 ft*lbs on the head instead of 65 ft*lbs, but most just torque them to factory specs. Completely pointless. And our engine has an iron deck so surface deflection is not of concern anywasy. And factory head bolts are more than substantial anyways.

Factory head gasket is a multi layer steel unit on all 1.8's, so it's good to go. Not a weak link by any means. O-ringing the block would be more reliable, but not necessary. Head gasket is kinda like the fuse of the engine anyways. I'd rather blow a head gasket then throw a rod. Easier and cheaper to fix the head gasket. But in serious racing you might rather take the chance of blowing an engine with a little knock then having to let out of the throttle or blow a head gasket. Up to you there.

Oil pump is gonna need to be billet oil pump gears if you wanna spin it 8-8.5K reliably. Granted the motor will make zero power anywhere past 7500 more then likely, so it's kinda useless other than having the extra rev range, but you reach a point of diminishing returns with power falling off hard and it's pure hell on everything in the engine. My advice is 7500 hard rev limit with a built engine and know it can sit on the limiter like that for many Sundays.

Compression ratio's are overrated. It's affects on spool are arguable either way. You don't race people in 5th gear at 2K RPMs. Once you're in boost the lower compression is better. You can make 300 whp on 11:1 or on 8:1. Difference being the 11:1 motor will have a very small margin of safety between max power and detonation city. 8:1 will run a couple pounds more boost, but you'll be able to run more timing and have a much larger safety margin against detonation, which some appreciate. FWIW there's a thread on FI and compression ratio's here, but it's long and ridiculous. In short lower comp is less efficient, but safer. Higher comp is more efficient, but less margin of safety and you reach a point where at some level of boost where the higher comp motor has to retard timing too much to keep from detonating and then the low comp motor will be ahead, again.

My stock valve springs would let the motor go to 7800 without valve float on my 99. With the headwork I did I lightened the valves and I've turned 8K without valve float. I could probably go higher but I have a stock bottom end. So unless you're gonna spin faster I wouldn't waste my money. Stock size lighter valves would be ticket for you most likely. No need to get bigger valves IMO because the stock sized valves are already "huge" in comparison to the rest of the head. Head doesn't need bigger valves. It needs a reduced short side radius and larger combustion chambers to reduce shrouding. Bigger valves only adds to the shrouding problem. And most machine shops won't open up the seats the mind blowing .040" larger to accommodate for the larger valves, which is where the gains are found. If they don't then bigger valves do nothing but add reciprocating mass.

Take all that with a grain of salt. It's my opinion. Worth about as much as you paid for it.

No, that info is worth alot to me.
I really appreciate you taking the time to write that up for me.

So I am thinking 9:1 CR then. Higher than I have now and known to have a fairly decent safety margin.

Were to I find lighter stock sized valves? I only see the oversize valves all over the place.

Thank you..

Turns,
Supertech makes a stock size back cut valve kit. For spoolin, headwork is going to be more important than anything else. And when you open up the head, you'll lower the compression ratio. So don't be afraid of 9-9.5:1 pistons. Also for more midrange power, I'd suggest the MSM intake cam and adjustable cam gears. It will fall off early, but it will be a big kick in the ass around the middle.

Awesome,thanks Ben.

This entire thing sure looks like it fits the bill..

What do you folks think??

BELFAB RACING PRODUCTS

OH, PS- I will likely run C16. Might as well right !?!?!

+1. Head work is the king of all mods when it comes to power. Helps everything. Stock my car is 9.5:1. I removed a shit ton of metal from the combustion chambers unshrouding the valves. Result is more flow, less squish, and less static compression. I'm surely around 8-8.5:1 now, even though I have "9.5:1" pistons. So yeah if you do get into modifying the combustion chambers you will be lowering static compression. If you do any combustion chamber work, you should CC the head and find what your new compression ratio will be. That will help you figure out what pistons to get. Or like I did I just know I'm at least a point lower than stock, but no exact number on it. Funny, cause static compression went up from 185 to 205 doing a compression test before vs after the head work, and it should have went down... My only guess is it flows better and more air gets in, offsetting the lower static compression.

I'm interested in this MSM intake cam. From my limited (read, not really sure think I read some where), it's extremely comparable to doing an exintake swap, no? Or is it that much better still? I got a spare 01' exhaust cam, as Ben should know, so I'm doing that one day.

Can I just swap that msm intake cam into mine and go with it??

Sure you can, or you can do the exh-intake swap. But I recommend adj cam gears since you want that midrange.

Yes. You'd want to check valve lash to make sure it's still acceptable, but it will likely be fine as both cams should have the same base circle. MSM has a different cam gear though. You need it too. Or as Ben said get an adjustable cam gear for it. Or drill a new locating hole in the stock cam gear 197.5* clockwise from the "I" mark. Or, as I'm gonna do, turn the cam gear till it's close to putting the cam 197.5* clockwise, then pick the tooth that's the closest. :) I'll be picking the tooth that puts the cam a spec retarded as that's good for top end power, but not good for low end. Everything's a compromise with fixed cam timing.

As he mentioned earlier if you tried you could build a middle RPM beast if you tried. That would be fun on a track coming out of a corner. A VVT head would be ideal if you could control it, as it will allow you to change intake cam timing based on RPM AND load. So you can have lots of low end grunt and top end power. But it would add cost and complexity that's not completely necessary.

Are you sure he'll need a MSM gear and it won't work with his stock one? IIRC that same intake cam is used in all '99-'00 JDM NB and I don't remember Randy Stocker mentioning him needed different cam gears at his web page.

Nope, not sure. Either will probably work. Just remember they are different and most that put the MSM cam in got the MSM cam gear or an adjustable cam gear.

It is always so much to think about LOL!!

If I have a turbo putting down the power(tq) soon enough and it follows through pretty well, I am still set with out changing cams.
That is originally what I wanted to to.

I think what I need to do now is find the correct turbo for this.

I will likely be going with a SPA turbo. I have a decent hook up there.

I will likely be using a .48 turbine housing. I just have to decide what compressor housing to use to keep forcing that air through that smaller turbine.
My friend is using the 70 A/R compressor with a .36 turbine. I think 22-24lbs of boost and making 270whp/290tq.

I figured a nice size compressor and the smaller .48turbine should yield me the 300whp and 270+whftlbs I want.

Again, I want full boost 3200-3500. That may be 14-20lbs LOL to reach the #'s I want.

I'm not sure how wise a 48 turbine will be with your power goal and intended use.

To spool up, what you need is headwork. I'd go with cam, cam gear, headwork, and a bigger turbine. Will spool up nicely and not choke, and will not have those super hot egt when you're driving the snot out of the car on track.

Cool, I will have to talk to my machinist and see what I can afford :(

If you are willing to invest a lot of your time reading and learning the basics about cylinder head modifications, you could do a lot of the head work yourself. Might not be as good as having a "real" professional do it, but HP/Dollar ratio would turn out nice. There's a lot to learn and there's a lot of misinformation out there. What works on some heads doesn't work on others.

I spent ~200 building my 99' head after buying a book, borrowing another, and all the bits needed to do the work. Oh, and 100 on a cheapo drill press to spin the valves to undercut them. So 300 bucks and I have an extra 20-30 whp and a POS drill press to show for it. Can't wait to get turbo just to see how this motor spools a GT3271.

Emilio just replied here:

MX-5 Miata Forum - BP5A-12-420 cam specs

The MSM intake cam is plug and play and doesn't need any special MSM gear. You can use your original cam gear and you don't have to do any mods to it.

Couple of points I disagree with.

1. Studs are re-usable. I like them for that reason and they make installation and removal of the head a snap. I like the fact that studs provide more even torque but as you note, it's overkill. It's the fact that you can reuse them forever that makes them worth it.

2. Built motor, 8500 RPM rev limit makes sense for ********... it's not that you make "no" power, but you make no additional power... 300 RWHP at 7000 is still the same 300 RWHP at 8000 RPM... for ********, this extra rpm can be useful.

3. Compression ratio. He is running VP109 race gas, so using an 11:1 compression ratio makes perfect sense unless he wants to run 35 PSI of boost. Really it will help the turbo spool earlier and it will make massive torque at relatively low boost. Once again, ******** is not about making the most power, just enough power to over-whelm the tires at will across the widest RPM band. If he was running pump gas, I would agree with you.

Mark

You're worried about cost but you're going to run $16/gallon gas?

Frank

Thats what I need..

Dont Mnet me Bro;)

Yes, in regard to head work. For my goals that much isnt necessary. SO I will do what I can afford..

Oh, and likely it will be 110 VP. Not C16. So it will be about $6-$9/gallon for me..