4G18 convert to DOHC head..

wrenwei87 · Postby **wrenwei87** » June 1st, 2011, 1:49 pm

bros..
need some opinion,my engine is 4G18 sohc ,but convert to 4G15 dohc head in year 2009..recently i did reflash original 4G18 ecu,after reflashing,my engine did have some knocking during high revving..what cause the problem of knocking ?issit ignition too high ?my tuner already lowered down the ignition ....knocking did decrease..but power decreasing too ..how to solve this problem ?i did install adjustable campulley for this DOHC head....please giv some opinion....thanks..

srnoth · Postby **srnoth** » June 2nd, 2011, 10:49 pm

wrenwei87 wrote:bros..
need some opinion,my engine is 4G18 sohc ,but convert to 4G15 dohc head in year 2009..recently i did reflash original 4G18 ecu,after reflashing,my engine did have some knocking during high revving..what cause the problem of knocking ?issit ignition too high ?my tuner already lowered down the ignition ....knocking did decrease..but power decreasing too ..how to solve this problem ?i did install adjustable campulley for this DOHC head....please giv some opinion....thanks..

Having a similar problem in my CS3 converted to DOHC. Had to retard the timing slightly from stock, but still get the knocking occasionally.

Float · Postby **Float** » December 21st, 2015, 9:52 pm

I have the same problem on my cs conversion looking to use bkr7e plugs (cold) and custum fit egr

fras · Postby **fras** » January 5th, 2016, 8:27 am

let me get this correct... yall did a head swap or complete engine swap?

if it wasnt knocking before u could restore to factory map/replace ecu, or try using premium n see if that makes a difference
maybe better off with a piggyback that could adjust fuel/timing

trini iceman · Postby **trini iceman** » January 5th, 2016, 2:52 pm

http://www.trinituner.com/v3/forums/viewtopic.php?f=33&t=653461

Get with the times. :lol:

fras · Postby **fras** » January 6th, 2016, 12:05 am

i have seen head swaps... just wanted to be sure of what yall talking about!
saw 4G15 and 4G92 dohc head swaps, both are a waste imo! ur better off modifying or swapping engine!

Float · Postby **Float** » January 6th, 2016, 10:02 am

fras wrote:let me get this correct... yall did a head swap or complete engine swap?

if it wasnt knocking before u could restore to factory map/replace ecu, or try using premium n see if that makes a difference
maybe better off with a piggyback that could adjust fuel/timing

Running premium, significant reduction in knock but still there ,working on retading timing.the engine loves premium it is almost as if it is saying "yum yum"(better performance) changed to 210 cc(cdh 210) eliminated lean burn situation.looking for greddy emanage blue, cheapest i can get right now before I switch to AEM EMS-4.

fras · Postby **fras** » January 6th, 2016, 1:35 pm

spending too much money for lil gain... better 4G18T or engine swap
4G93 sohc selling cheap (7k) making more power and it's good platform
4G92 mivec & 6A12 mivec are the top n/a contenders (10-12k) engine, ecu & harness

would love to run 1 of those dohc 4G18 with my sohc

Float · Postby **Float** » January 6th, 2016, 10:17 pm

fras wrote:spending too much money for lil gain... better 4G18T or engine swap
4G93 sohc selling cheap (7k) making more power and it's good platform
4G92 mivec & 6A12 mivec are the top n/a contenders (10-12k) engine, ecu & harness

would love to run 1 of those dohc 4G18 with my sohc

I was planning this for years so I am not naive(no offence taken) I am a Tobagonian I live in Castara
12 miles from the capital(country)lot of hills and corners so my project is about high speed cornering and ample torque(150 ft lb).With that in mind 6a12 v6 will make my car too front heavy(car points into corners better with less weight in front eg.cs6a gdi turbo on the same coarse tend to under steer handled well but under-steer was prevalent and also when i did gearbox conversion car was more responsive to steering input. Next 4g18t(think you mean 4g93T) is the best idea but would not work back with the ABS(ECU and ABS ECU),4g93 sohc only produces 118hp with 117 ftlb of torque I can easily get that from my current build and the availability of DOHC conversion is slim,can make a better turbo project cause of bigger displacement (1800 cc) but weight conscious, although i saw a 4g93 dohc in a cs9a in russia (FIRST TIME I EVER SAW ONE with cams on right hand side ) and 4g92 mivec nice but ABS communication probs just like 4g93t(ck model engines).Not willing to give up ABS cause my car came without it and I had to painstakingly install it myself

so in essence was trying to stick to the cs side of things so to speak , if I had a ck no probs but I choose cs because of more rigid chassis which I perceived as better for handling.My aim is to go turbo to get the torque.You might say little gain but almera(qg 1.6) tiida 1.5 and 1.6 autos was putting bad licks on my 4g15 sohc gearbox now i run passing them no longer have any respect for them my pros are
1. more torque from 4g18 stroke 87.3mm vs 4g15 82mm(main reason for build)
2.More responsive like a 4g92 mivec(same sharp response and sharp exhaust sound)
3.still have room to work in my engine bay( thank god so repair work is not so hard)
4.MPG is still acceptable even with premium
5.learned a whole lot about engine modifications and gained the respect of a lot of top level mechanics on the island.
6.last and not least loving the third gear pulls on highway sound sweeter the more it revs (which it likes to do) the power is kinda high up in rev range 3500 on wards to 7500 rpm, coming from a 4g15 92hp sohc engine this is a lot, every time I drive I have to smile it is sooooooo sweet, now is not just point A to B it is miles of driving pleasure

fras · Postby **fras** » January 7th, 2016, 7:30 am

no, i didnt mean 4G93T (those engines like gold & parts even harder to get) turbocharging your 4G18 is the best bang for buck!

i guarantee your 4G18 dohc with intake & exhaust mods will not beat a 4G93 sohc... so what then?

thats just my opinion... if more hp/tq is your goal, better start with a better n/a platform of turbocharge your 4G18!

Float · Postby **Float** » January 16th, 2016, 7:18 pm

the pics

Float · Postby **Float** » January 16th, 2016, 7:29 pm

https://photos.google.com/photo/AF1QipM ... iH1KqI9tIM

trini iceman · Postby **trini iceman** » January 16th, 2016, 8:35 pm

Castara ent too bad, lived Lanse Fourmi, honestly I would've loved to take my FTO when it had the 6a13tt on those roads but I'll have to do it with the 2.4 4g63/64. Anyhow the platform limits the amount of power you can get away with. Everyone said the FTO would be such a pain to drive with the 6a13tt but it handled pretty good but at the end of the day it was setup for a v6 (6a12 mivec).

Build a car you can enjoy.

racedriverpro · Postby **racedriverpro** » January 16th, 2016, 10:57 pm

Op yuh beat up any Sr men yet? Just curious

Sent from my C6603 using Tapatalk

Float · Postby **Float** » April 23rd, 2016, 9:15 pm

Nope cannot fight a QG18 in a U14 much more in a b15/n16 so SR is for when I turbo ,building another 4G18 DOHC but using GDI con rods(1.5) and CK2 1.5 DOHC piston crown do not know what crank yet GDI or stock crank.In the workshop manual it says the 4G18 and the 4G13 are similar in crankshaft so if i use any 1.5 crank i think i might reduse my displacement of engine,have all the parts but to beat a normal silver top SR with a 1.6 turbo have to come good but tuning to challenge SR red top N/A in a B14 soooo yuh know it serious ,have to buy stand alone management so might not put in till year end ,have to save hard but I very much intend to defeat the SR in a quarter mile .