Rep Power: 271

hey guys. i was wondering. which head would be better for a boost set up? i am currently running the ex head on ym car right now but a friend of mine has an lx head jsut sitting around and he said i could take it if i wanted to. since the lx head would lower my comp a bit that means i could boost higher correct? are their any other factors to look for in a head besides the compression factor? what set off the ex head from the lx head in a boost app and what are the pros and cons? i was thinking, since the ex head has vtec-e it probably might not be the best app for a turbo set up, unless of course you get the turbo cam which costs an arm and a leg. i am still pretty noob at all this stuff. yeah i searched but i couldnt get what i was looking for. thanks for any help

 
Rep Power: 297

well lx block would be best cause it can hold more compression. then an ex head would be ideal since you can use a crower stage 2 cam.

 
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Keep the EX head bc you have lil higher redline and the ex injectors are bigger than LX injectors but you'll probably be running rsx injectors anyway.

 
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i have emanage and rsx injectors awaiting installation all i am waiting for is my emanage harness then i am good to go @ 8psi. if i bolt on a block guard that would reduce my compression a lot to handle more boost correct?

 
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Not so sure about that but there are alot of boosted guys here that can give you better information...however, I don't think you should be worrying about compression if your just running 8psi.

 
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i was told that 8psi on a stock ex is actually pretty high so i thought i should ask. better safe than sorry. i guess we will have to wait for some more turbo dudes to get in here

 
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mostly people run 4-6psi. then it can go higher. most with stock internals on an ex, d17a2, i saw was around 12 psi. but after 8 i would say build up the internals and have a good/safe tune.

 
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BLock guard won't lower you compression, and I dont THINK that an LX head will lower your compression either. It might but i dont know.

 
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**** I say EX block EX head with Vtec in mind....

Even tho the LX has a higher compression...

 
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The Lx which has the d17a1 has a 9.5 :1 compression ratio and the Ex which has the d17a2 has a 9.90: 1 compression ratio. And as far as I know changing from a EX-LX head will not lower you compression ratio.

 
Rep Power: 423

First of all, the block guard doesn't lower the compression. It just supports the top of the sleeves because the engine has an open deck and with excessive boost the sleeves can walk. You're limited boost wise by the stock hardware anyways. The head lifts and the rod bolts stretch, when it all comes loose, **** goes in a hurry. The VTEC vs. no VTEC is a strange issue. No VTEC makes the tuning easier, VTEC gets you more parts and better airflow. Either way obviously works, but there's no difference between the 2 engines. Its not like the B18B and C where the B's dimensions lend itself much better to boost than the C. Either engine works fine, its been shown that either of them can be built to make quite a bit of power when done right.
With a stock bottom end, I wouldn't go past 6 if you want the thing to last.

 
Rep Power: 350

I ran 13.5 psi boost on stock motor. Held together fine except that cylinder 4 was leaning out due to a stupid problem I wasn't aware of....but boiler is pretty much right on other than that. Your compression ratio is based on your pistons with these motors, not the heads. Combustion chamber volume should be the same, regardless of the head.

 
Rep Power: 271

oh. i thought that since the blockgaurd raised the head up a bit it would lower the compression. because i always heard of shaving down the head gasket to increase compression. i think i will run 8psi tuned with emanage rsx 310cc injectors. i was thinking of going higher but i only have a dsm sidemount intercooler. it might not cool the air enough to run safe daily. my engine knocks when its cold but goes away after about 30 seconds of warming up. also my turbo lags a lot [t3 .48ar]. i get to full 5psi at maybe around 4.4-4.6 rpm however i think the age of the turbo is effecting the spool up times because it is a 20 year old turbo, rebuilt though. wanted to know if any other factors beside the age of the turbo effected spool up times. the way my turbo spools up seems rather late compared to all my friends turbos who are running bigger t3/t4 turbos and they get to full 10psi at the same time i get to full 5psi with a smaller turbo.

thanks for the info everyone ... i am looking to learn more as i am trying to learn from my set up now. this is my first turbo car so yeah.

 
Rep Power: 350

Where are you getting ur info from? A blockguard doesn't lift the head at all, how would it possibly seal to the block for compression? Also, you can't shave a headgasket to lower compression, you have got to have those seals for the same reason.

Spoolup time, how are your vacuum lines routed for boost control? What are you using for boost control?

 
Rep Power: 271

i guess im talking to the wrong people then. sorry. lol

i just running off my external wastegate. the line from the turbo to the wastegate is only about say.... 4-5 inches long. i dont understand why my spool up times are so long. even when at about 4k rpm cruise then WOT it takes maybe about 3-4 seconds for full spool. someone told me to zip tie my vacuum lines so they wont expand as much. maybe i will try that, but im sure it wont have a major impact

 
Rep Power: 350

Well, for one, the wastegate is seeing the pressure at the turbo. The pressure coming off the turbo is not the same as the pressure going into the intake manifold, hence, the wastegate is opening alot sooner. You need to run a T into the vacuum line from the back of the manifold to the wastegate and cap off the fitting from the turbo. You will instantaneously see a dramatic increase in spoolup time just by doing this, BUT YOU HAVE TO RUN A BOOST CONTROLLER OR YOU WILL RUN WAY TOO MUCH BOOST!!!!

All that zip tieing a vacuum line is going to do is make a better seal and prevent it from blowing off. I recommend doing that though, all of my vacuum lines are zip tied and I've got alot of them.

 
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if this is some shop telling u all this....RUN!!

 
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wow! Thanks for reinforcing why i ditched the d17. 6-8psi on a stock block is pretty weak. K series FTW.

as for your question, neither engine is going to make that big of a difference. Just stick to what you have.

 
Rep Power: 271

andy so your saying block off the turbo line and run the waste gate to where i have my boost gauge hooked up to maybe? how will i see more boost if i do this if the wastegate is only a 5psi spring? i mean since the spring is in there it shouldnt even see higher than 5psi right? my bosot gauge reads 5psi all day, well it actually says 6 but the gauge reads 1 if you know what i mean.

f this is some shop telling u all this....RUN!!

^lol dont worry no shop is telling me this. i was having a talk with a couple dudes at some meet yesterday and they were telling me all this **** i was like wow i always thought it was like this blah blah blah when in fact i was right the whole time. ahah.

lol well all good things come at a price. there is hope for the d17 im sure. at the races the quickest car out there is a red eg running mid 11 with the d16. CRAZY