Quote:
Originally Posted by hotdoghogie
if you get an aftermarket MSD box they have built in rev limiters
Printable View
Quote:
Originally Posted by hotdoghogie
if you get an aftermarket MSD box they have built in rev limiters
i just took a look at the head i just disassembled. apparently ive got double springs in the exhaust
The A20 exhaust double springs are much weaker than the 2G prelude A18/ET valve springs. I've gone over this a few times, the A20 valve springs are not designed for high revs reason why the rev limiter is there, carbed engiens aren't rev limited so to protect them a bit better they have stiffer springs, ET1 has double springs all round but they aren't particularily stiff, but if you use Prelude exhaust springs all round you'll have a setup good for 8-9k rpm, if you want a setup for 7-8krpm then use A20 exhaust outer springs with Prelude exhaust inner springs or stock A18/ET2 springs all round, if 6-7k stock is fine or ET1.
so let me get this straight, you can use prelude exhaust springs all around meaning i can use them as an intake spring as well? is anyone using this setup yet?Quote:
Originally Posted by rjudgey
yeah, so my accord has no rev limiter and will rev over 8000 rpms if i dont watch it. take for instance when the tranny is cold it wants to stay in gear, it is automatic. a couple of days ago i started the car and hadnt driven it. i was getting onto the road and trying to speed up for the traffic that was comming, reved nearly 8000 rpm with 1st gear going nearly to 60 mph. kept pulling. anyways, do the accord A20A1's have the double exhaust valve springs? never really took a look at them, havent had to yet.
If you use the double springs all round you'll need platforms and retainers from ET1 for the inlet springs, if you do the exhaust to inlet valve conversion which i developed you can use the exhaust double valve spring platforms and retainers.
http://www.hondaautomotiveparts.com/...LVE-ROCKER+ARM
so what numbers would i be needing? i dont really understand the platforms part, are they the part the springs sit on directly?
im sorta reading this over and over again... is there any benefit from using the entire exhaust valve side on the intake side rather then just swapping out all the ET1 stuff over to the A20 head?Quote:
Originally Posted by rjudgey
if i plan to use double springs all around, is it recommended that i replace the exhaust side as well?
what happens during valve float? i know the valves arent closing fast enough, but what actually happens during it, everything gets compressed back into the intake and smashed valves? how do you know prelude springs all around would go up to 8-9krpm? with my soon to be newly rebuilt engine, id like to play it conservatively, but id also like to kick it up a notch from stock form
Quote:
Originally Posted by rjudgey
im kinda not getting this contradictory statement here, especially 'ET1 has double springs all round but they aren't particularly stiff, but if you use Prelude exhaust springs all round you'll have a setup good for 8-9k rpm'. if the ET double springs all around arent stiff, then wouldnt the prelude be no exception as it uses the ET engine as well?
sorry if im just being a retard, but that entire quote above is kinda hard to understand(atleast for me). your telling me to use prelude exhaust springs all around since i want a setup for 8-9k rpm, thats great, thats alot of help there as it is(wether its been tested up to this rpms is a different story). you state that they come in a prelude, but you also say that the ET1 springs arent that stiff and good for 6-7k rpm. you also say that the ET2 springs are only good for 7-8krpm.
from what i understand as of now, preludes came with either the A18, A20, ET1 or ET2 blocks. if none of them are good, then what am i supposed to use, unless what your saying is i should use the exhaust springs from the ET1 preludes and skip all the intake springs. is that it, use prelude exhaust springs from the ET1?
i think its time for me to hit a junkyard soon... BTW, when i was back in school, my mechanics teacher told me that alot of parts are 'worn in' parts, things like bearings, valves, and a few other things that have to go back to where they came out of. are springs transferable between heads without having to recondition anything?
once again, im sorry for being a retard, but i just wanna get this straight before i blow up my engine
a quick search on wikipedia tells me that the A18 engine came in the 84-87 prelude. it also says the ET block is found in the 85 prelude, what gives? any particular block to take the springs off of?
i guess aftermarket is safer...but it would be cool if you can swap in other springs off a honda....
so im gonna go look for prelude exhaust springs soon, but i just dont know which block to take it off of cause it seems so contradictory at this moment
Right first of A18 is from 86-87 ET is from 83-85 and ES1 is from 83-84.
ET1 is a 2nd Gen Accord engine not Prelude and these were from 84-86.
A18 and ET all use the same springs they are all really good,
ET1 has double valve springs but the rates aren't as good even though they are double
A20 has even weaker springs than ET1 and a lot weaker than A18/ET but some variants like A20A3/4 had better springs.
The double valve springs can fit any double valve retainers and platforms from ET1 or A18/A20/ET/ET1 exhaust platforms or ET1 doubel valve spring platforms and retainers from the inlet side.
I know what works and what doesn't as i have tested all these different springs at different revs with different cams, i have built more engines for 2G prelude than you can imagine at all different stages.
Just get a set of A18 prelude springs they'll work fine you'll never build a 9k rpm engine cause you won't know how to and even if you did it would destroy itself very quickly. I've built and blown up every engine i've made for 2G lude not because it was poorly built just because i wanted to see how far i could push it and to see what part needed modding to make more reliable.
I have had Big valve conversions done on my heads using old exhaust valves and there matching platforms and retainers this mod works extremely nicely but requires specialist machinig which can 't be done by hand.
If you want high revving upto 9k you need Prelude exhaust springs all round from A18 or ET head i've found these to be incredibly stiff and i have used these upto 8.5k rpm without any trace of float and i've even had a friend miss shift from 5th to 2nd which revved at about 10k rpm and the valves were still in one piece.
thanks for clearing it up for me there rjudgey. now that im not so confused anymore, i guess ill be hitting up preludes with the ET blocks in the junkyard.
just to make this a bit more clear, honda made an ET block for the prelude and an ET1 block for the accord right? sounds kinda weird that honda would make 2 different variants of the ET.
anyways... what does it take to build something to reach 9k rpm? wouldnt the only thing you need be a perfectly balanced bottom end, and possibly forged pistons/rods(if that)?
the build that im doing is basically a stock-like rebuild with OEM equivalent parts, what rpm is that capable of reaching safely?
Honda made even more variations of the A20. And in fact all of the above are nearly the same block, just a larger bore diameter for the 2.0L vs 1.8L.
9k would take far more than just valve springs to be even remotely reliable. You would need a drastically lightened bottom end with serious balancing. Then you would need major headwork to make use of the extra flow at 9k. Big money here.
C|
so im planning on doing 7500rpm, would the stock balanced oem bottom end be able to handle that, or should i atleast lighten the flywheel? also, id need springs from the prelude block(ET or A18, NOT ET1) specifically right?
If you want to rev to 7.5k the stock rods will only last 20-30k miles thats how long mine lasted the rod bolts aren't the problem the rods snap off just below the piston which is the area where they are the thinest. Pistons are okay upto 7.5k but you really need to get aftermarket rods. 9k rpm will need titanium wrist pins and rods and then your talking $1500 just for those alone probably a bit more.
ok... so i guess ill stick with the stock redline for now then... or possibly up the redline to 7k from 6.4k, hopefully thatll live a while
my next build, ill be running custom forged low comp pistons with eagle rods, so hopefully thatll survive it all.
out of curiosity, if i were to bring in a set of eagle rods to my machinest, can he bore out the piston pin hole to make it fit and still retain most of the strength in the piston?
Not sure with cast it's possible but don't know if it will last long? You could have the rods re-bushed and maybe convert the stock pistons to C clip, for the price of a new set of honda pistons it's not worth cheaping out might as well pay the little extra and have forged ones.
Quote:
Originally Posted by rjudgey
true enough, for now, i think im gonna stick with the stock bottom end and boost it until it blows. meanwhile for the top end, ill be using prelude exhaust springs all around. if i can go a while without head failure, i guess ill install double springs on my built head for my next motor build which would probably hit 7.5-8k
thanks for all the help and clearification man:rockon:
would springs from an ES1 work as well?Quote:
Originally Posted by rjudgey
i just went to the junkyard, and i took valve springs from an A18A, and an ET, but the last one was from an 84 prelude. so its quite possible that it came from an ES1, would that work as well?
POssibly but we never had ES1 in U.K. so i've not been able to test them? If you ahve the spring rates measured and they are the same then yes, but as the ES had an extra 4 exhaust valves to push to recycle the exhaust gas Honda may have used weaker springs so that the engine didn't loos too much power to friction.
so it was 16 valve from the 4 extra exhaust valves?Quote:
Originally Posted by rjudgey
Technically yes but no as instead of letting the exhaust gas out into the header it would recycle part of the exhaust gas back into the chamber and mix back in with the fresh air and fuel coming in. Which is totally fooked up don't know what honda was thinking here? Didn't make them for long only for a few years for LA smog laws then i think they realized that having better ignition and other upgrades to the design was more than good enough to meet smog, plus all the complaints about engine overheating and head warping pretty much killed off the idea too!!! Not too mention the lack of power as well!!!
