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Building an N/A Omni

13K views 44 replies 14 participants last post by  Vigo 
#1 ·
I got myself a real clean 87 dodge omni, its my daily driver so it dosent have to be a rocket(thats why it will be n/a). I just want it to have a little more umph. This is what i plan on doing:

I already have the Weber 32/36 and Bosch SVDA distro swap so there is not spark computer anymore

I have the 287 "G" head and im raising the c/r, thinking 11:1 so i can still run on premium. Port match, may possibly port and get bigger valves.

port intake and remove center section from plenum.

port exhaust manifold and 2.5in manifold back exhaust

adjustable cam sprocket to retain correct cam timing after head milling

FWD performance F-3 cam (kit with the cam,lifters,rockers)

Crane HD valve springs(from FWD performance)

underdrive pulley

remove coolant lines from intake and either wrap the intake or make a heat barrier to keep the air/fuel charge cold

modify valvebody for firmer shifts and the biggest possible trans cooler :thumb:

thinking about removing center of thermostat so car will run much colder? its like 5 dollar trail and error so ill see the results

new plugs and wires, Any suggestions? not sure which route to go here.

an MSD spark box the AL-2 i think the model is

higher voltage coil

and air/fuel guage for precise fine tuning

Also for the 11:1 compression, i heard that with non-turbo valve they may possibly burn? anyone have any ideas? this makes me want to get an EGT to make sure that dosent happen.

i have 4 lug pizza wheels imma put on and lower the car and then get a strut tower bar and a shock tower bar for the back

now right now my major concern is the raise in compression. i plan on getting the MP 005 headgasket which i believe is .015 thinner compressed then stock then mill .060 off the head for a total of .075 which will take me from my 8.5:1 to 11:1. I may have my info wrong but as far as i know .030 is good for one point in compression? Anyone know if im correct or not?

and thats about it for performance, theres little odds and ends i may be forgetting Any suggestions or concerns anyone? any help would be greatly appreciated. Thanks
 
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#2 ·
I wanted to build my Omni into a damn fast daily driver (it's a 1990)... I don't have any advice on a build but after looking around junkyards and a few people's help here it was cheaper and more powerful to rebuild a T2 and drop it in.
Omni's Rule!!
 
#3 ·
Been there and did a lot of research building a carb 2.2. I know you probabily dont want to hear this but just do a turbo swap. A stock T1 will make more power, be more driveable and even be able to run regular fuel for less money. Keep an eye out for a complete T1 motor, get a harness / ecu's and install a electric fuel pump. You should be able to pick up a good complete T1 for a few hundred dollars and one that needs rebuild even less. Since fuel injection was available your year atleast in the turbo cars, the right harness "should" be plug and play. I played with carb and TBI motors and ended up swapping in a turbo engines. I would never look back. I have a TBI daily driver I thought about playing with MPFI but with the work involved i might as well go turbo. If you do most of the mods listed below to the turbo ( except the high compression) you would have one nasty car.
 
#4 ·
Hi there, the factory HO engine (we have one in my daughter's Rampage) is decked .035" raising the compression to about 10:1. The problem is, you have to have the correct input manifold (with TD Knock sensor), the matching computer (rare) and the engine wiring harness. If you don't have the stock ignition system you will probably have trouble with knock even with 10:1 compression. The Rampage uses a 5220 carb and the timing is really sensitive - you have to be spot on to not have knock, but still have acceleration and she burns midgrade fuel. Best advice has already been given. If you aren't happy with what you have now, go the Turbo 1 route. Best you are going to get out of a NA engine, with all the expensive mods is another 15 HP or so. The turbo 1 setup will immediately get you 30+ HP and you can use the cheap gas. Seriously cheaper in the short and long run.

For my Rampage, I installed a 2.5L engine, pulled the balance shafts and went with underdrive pulleys. I figure I have about 110-115 HP now and it was an easy swap - about $450 for a low mileage engine. Good match for the truck, especially when I am hauling 600# of cinder blocks up hill.
 
#5 ·
Lol everyone on the site will, unfortunately, tell you to turbocharge the car. I won't tell you to do that, just because that is what everyone else will do, and I would be pi**ed off if someone replied to my thread after saying that was building an NA car.

I know for a fact that you can get an NA up to the horsepower of about a t1. I've never heard of anything higher. The biggest problem with that plan is that your going to be dropping big $$$ into the car, more than its even worth. And that is why everybody just goes turbo, because its probably less expensive.

The list of mods you have there seems good. A more aggressive cam, ported intake, better head, bigger exhaust, better carb. Obviously, the most important thing to remember is that the more flow/ less restriction you have, the better. I'm not sure how much power you will be making on all those mods. Unfortunately, I also do not know anybody on this site that builds naturally aspirated cars.

Oh and one other possibility, there's a lot of debate about carb vs fuel injected. But you could consider a conversion to mpfi.
 
#6 ·
We have 2 motors, both 2.5's, but their for roundy round, one at 10.5:1 and one at 12.5:1. The 10.5 motor we ran on premium pump gas and raced it for 2 seasons with no issues. The 12.5 one I run on blended fuel to make it just over 100 octane. IMO 11 is close on pump gas but probably doable, with aluminum heads you can run more compression without detonation and if you clean up the head to eliminate hot spots you should be rigth about there.

My experience says that you can bump compression, cam it and all that but the NA cars aren't good at getting needed stuff in or out. The carb or TBI, whatever your running is a big limiter along with the intake manifold, it's transition to the head then that exhaust manifold. Looks like you have that covered with your set-up though.

We have a street turbo car and as much as we like that I honestly enjoy pushing the NA motors. I wish i could put our current 12.5 motor on a dyno and really see what it does, I suspect it is pretty stout. It took a couple races to reset the car for the more HP and work out a bug, but in the last race we passed a DOHC 150 HP Neon on the outside and out ran a 165 HP Nissan....so probably not doing to bad.
 
#8 ·
Any statement would be a guess, I've never dyno'd or can't say I've even run it through a engine simulator program.

But if someone wants to shoot daggers at me I dare say based on measuring its on track performance against other known cars it is pushing north of 150. Thats with quite a few mods hinted at above but a home port polish on head/intake, the TBI is bored, 12.5:1 CR, oversized valves that are deshrouded, windage tray, no balance shafts, long tube header......
 
#9 ·
I was right there with you until i heard it was automatic.

That KILLS it. The only way a 3spd auto remotely works on a 2.2L is if you have a bunch of torque from a turbo.

In complete seriousness, the difference in 1/4 mile times between an auto and a 5spd version of the same car, is about *2 FULL SECONDS*

A 5spd swap is the single biggest performance upgrade you can do to that n/a car. If you swap a 5spd in it will get a LOT faster, and you'd be hard pressed to mod the motor itself to ever get THAT big of a performance improvement.

I used to have a g-tech and i timed my non-turbo 3spd auto cars. They ran from 19.2 to 20.0 1/4 mile before any fiddling. Best i got after minor mods was an 18.7. I later put a 5spd on one of those cars and did 17.0. Those were heavier k-cars. Omnis are faster.

a carb/5spd omni is in the 16s stock. Several people have gotten into the 14s with n/a omnis, one into the 13s. That is pretty tough..but it would not be hard to build a 15 second n/a omni... *IF* it was a 5spd.
 
#10 ·
ok so i did some more research and .060 is equivelent to 1 point in compression, my motor stock has 9.5:1 so i shaved .060 off the head and went with a stock thickness headgasket, so im looking at 10.5:1 right now, also yes i know that turbo is the cheapest and most efficient way to big power but everyone does a turbo swap, i want something different, and also btw, i have an 89 dodge omni thats in even better shape with less miles, thats going to be the turbo swap car. Im going N/a on this one because i want to get away from computers and go with a completely non-computerized car, thats the reason for my vw distro swap. as for the auto in the car, yes i know its a turd with the most granny gears on this planet, id like to convert to manual but not yet, maby next winter.

All in all, i could have turbo swapped the car for less but i think its unique to have something different, if i wanted to conform to the population id buy myself a 350sbc
 
#11 ·
and also, correct me if im wrong, converting to turbo from a TBI car is easier to do than a carb to turbo swap? also for my n/a build, im looking around for the b&m supercharger for the car, then i can get a headshim to lower compression back down and it should be a quick little bugger
 
#12 ·
I had gotten old Matchbox into the high 13s but eventually got tired of all the breakage problems I was having. It kept twisting the cure support apart and bending the heck out of the bottom of it. It was breaking motor mounts and the dog bone support was bending double all the time until I had a bunch of metal bracing added all around it. I also broke 11 of the 5 speeds in 100,000 miles. At that point the cylinder walls were worm oval shaped and there was WAY too much blow by so in went a newer 2.2 from a 87 WITH a automatic transmission. That drivetrain slowed it down to...ugh...18.0! A COAN convertor, Lambros cam (from the 13 second set up), headers (also from the old set up), put it into the mid 16s. At the 200,000 mile mark that motor also was worn the same as was the transmission. In went a 87 2.5 tall block and its attached automatic. That motor we did not touch except for much larger jetting. With the stock 410 roller it would go slower when shifted at 5000 + than it did at 4750. The best it would muster was the same 16s. The addition of a FMVB has allowed the transmission to remain good. I must say that the TB 2.5 and transmission came from a friends mini-van that got t-boned. The motor had 235,000 miles on it but he had just spent a fortune rebuilding the trans. The BIG trouble with the TB 2.5 is piston slop. I put in three sets total and near the end of last year we stuck in a under 40,000 mile 2.5 from a Shadow. We left the BSs in it and did nothing else. The carb actually need less jetting. The old tired motor had slowed to the low 17s and the new cmmon block motor returned it to the mid 16s again.
 
#13 ·
I talked to B & M reps at the IMIS show in Idy and mentioned that they should make a smaller blower for us four banger guys....they DO! The smaller blower is a 371!

As far as plugs and plug wires...I used the stock wires, replacing them every 3 years (even though they were always good)..and used either the stock RN12YC Champions, or Accel U-grooves for the 318. Bosch platinum or ANY platinum never worked well in my carbed cars or turbo cars. The stock coil is HARD to beat. I was having trouble with the wifes 81 K-car and stuck the Accel monster coil (the big yellow one that's finned) and it did not help..the carb was the problem. I asked them to compare the two coils on their machine and the stock coil was much high voltage than the Accel! I put a stock Mopar coil in place of the Accel coil that was on my tubbed out Chevy Monzea and picked up nearly a 1/4 of a second! I gave the Accel to a friend that had just bought a brand new one and he saw no slowing comparing my old coil to his new one. I let him the stock Mopar one and he picked up two tenths! As far as the MSD ignitions, why do you think NASCAR guys have two set up on their dash with a switch to use one or the other? Because they tend to fail. I don't know if theystill have that problem.
 
#14 ·
I forgot to mention that I use a 180 degree thermostat that we drill a couple of 1/8" holes in near the main opening/closing section. This allows the hot coolant to seep by even though the thing is closed....it helps prevent headgasket problems that sometimes occur when hot coolant is pouring into a relatively cold block.
 
#17 ·
Hello, I'm new here also, so please forgive any FUs - Anyway, On running cooler - does your car have AC? If not, a larger 2 row like a Spectra CU656 will fit - new on eBay now for $59.32 total #400274239253 - Spectra has a good look up - http://ecat.spectrapremium.com/ - A CU656 will fit the AC cars, just hard to find new&low price right now - Both are a little bigger than the CU867 that's in my AC AT Rampage & both are all metal, have the AT cooler & Heater return nipple - - PLUGS - lots praise in Sticky: 2.2, 2.5, 3.0L guru's-need your input for a n/a FAQ hop up thread @ begin of the forum & other threads for NGK ZFR5N & AUTOLITE 985 Plugs - Same plugs I'm running in my Jeep - was a little afraid of the long reach & the snake oil claims - But they work-Definite improvement - Picked up 3-400 idle rpm, 1/2 to 1 mpg & haven't had a cold since - - This link http://www.innovatemotorsports.com/forums/showthread.php?=12128 was a big help for me & my DFEV 32/36 install/fine tune - 5 blade neon rad fan - Cherry Bomb GP r some other mods I'm running - The shift kit is a temp for me-I've a link somewhere for the home made conversion & other mods - will find & post if wanted - didn't mean to turn this into a book - :thumb:
 
#18 ·
A full manual valve body has allowed my 2nd automatic transmission to go nearly 100,000 miles with no browning of the fluid and no burning smell at all. The first auto that was put in lasted 100,000 miles until the thing was totally worn out from clutch slippage. As far as radiator....my 84 Horizon with the HO powertrain only has a single radiator listed at ALL car parts places....when I needed one the replacement was not as big as the stock one. (My car is no AC) I then ordered one for the carb GLH and the correct one came in.
 
#19 ·
Yeah, I understand the car parts thing - it's sad - The counter clowns & phone monkeys haven't a clue & if you can get your non standard/listed part then no warranty-no nothing period even if it's sold damaged - NONE of the car parts places will list Autolite 985s for my carbed 2.2 rampage same as the Spectra CU655 radiator, but both fit and work well - My truck is dealer added AC & the rad is a tight fit-v close to the compressr fittings but it works - only diff is a longer top hose from a k car & the heater hose return fitting is lower on the rad owise same 1 inch inlet-same 1.25 outlet bent 90 & AT cooler lines & temp fittings the same-I did add a few extra fasteners top & btm-no biggie & I'm no mechanico grande - didn't need it, just saw the unit as a cheap upgrade - - Anyway, the Spectra site is a good ref for ideas & dimensions/dementions - - - Don't know if a good oil filter cross is on Turbo, so JIC here's a link to WIX - gives specs, apps & you can correct them if an error or omission is found. I can't include urls yet so just go to wixfilters with the usual 3w dhotkom b4 & dhotkom after - here's another for shocks: monroe & after the dhotkom /catalog/Misc-information -then click on the 1st link;mounting and length sheets - great source for cross ref & ideas - used it back when to fit air shocks to my Triumph Spitfire - If I'm unclear on anything just em :D
 
#20 ·
ok so yes i do have AC, i questioned about running cooler because of my underdrive pulley and possible overheating at idle.

For the Plugs i decided to go with the NGK ZFR5N

I may possibly throw on an aftermarket rad fan(smaller and less noisy)

The link for the carb tuning didnt work for me?? maby its just my computer


And also for the running cooler, i dont think ill have a problem because even in 100 degree weather with the AC blasting at idle my car has never once went past the halfway mark, and yes it have a good thermostat, changed it because it stuck closed and thats the only time it has ever gotten past halfway(it actually went to the red, then a bit further lol).

As of right now the only thing that needs to be done with the powertrain part of the build is wait for my dang cam to come in and the trans mods
 
#22 ·
Nice pics - Giving me ideas - Anyway, the gist of some Weber posts of what worked/helped others & myself is in this forum under "weber once again" - The settings I found that worked best for my truck are last - - - - Are you running vac to the omni's distributor? That conversion is coming up for me - still not sure what ICM will be used - What fires your set up? I'm still learning & reading/looking at all I can find. So far I've just moved the coil - mostly to make room for an oil catch - Tight fit - probably been done before - heres a few pics - any suggestions/cautions are welcome :D
 

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#24 ·
First off, sorry for no reply in a while, been real busy making that $$$ to fund all my cars.

Yes i am running vac to my distro from the ported vac line from the carb.
Im using the stock coil with my distros +@- hooked straight to the coil(distro has internal control module) I keep the existing positive and remove the original negative.

Now the tach dosent work but all i gotta do to fix that is hook up the coils negative to one of the three wires that came off the stock distro(havent done this yet but it makes perfect sense, so dont take my word on it till i can say for sure)

For the supercharger, i PM'ed you.
 
#25 ·
I also think that I failed to mention that Matchbox has been raced for MANY years with no timing advance! I was tired of the computer failing at the wrong time and not giving me any timing, so I said to heck with that and pulled off the vacuum line and pluged off the ends at the carb. It is strange that when we tried the old hot rod trick of raising the base timing made the car nearly as slow as my 3 banger Geo!!!??? We have it set at 12 degrees base timing. The short times are sometimes in the 2.1s...with an automatic leaving at only 2200 rpm and since it still has the stock roller cam it runs its quickest shifting at only 4750 rpm. Someday I might get my Matchbox a gift of the Mallory distributor to make more power once I get off the line....but I might not since it took many years to get it this consistant....consistant = $$$$$$$$$$$$$$ in bracket racing!
 
#26 ·
In regards to a couple of earlier replies, a cooler thermostat will work better than removing the center. IF you don't have a computer, a 180 degree will help a denser fuel/air charge get into the cylinders. Alas, if you havea computer that controls warm up (all F.I. engines and a few carb. engines) you will slurp fuel like a pig. The engine will stay in open loop mode and never get the full power it is capable of.

Second, drilling holes in the thermostat body. This is actually a good idea. If there isn't a jiggle valve on the thermostat, I drill a 1/64 hole in the body of the thermostat and make sure it is at the top when installed. What this does is let the air burble up so you have water on the metal tube in the metal instead of air. Air is a good insulator and the engine can overheat before the t-stat opens. When it does finally open, water will blast out of the radiator, thermoshock the cylinder heads and do all sorts of nasty things inside the engine. This may not destroy the engine right away but it shortens the service life.
 
#27 ·
Ok so ive dissapeared from this site for quite some time, ive been waiting sooo long for my camshaft, Thank you FWD performance for taking nearly 5 months on my cam...

Well anyways car is up and running and on the road again and i have some issues.

First, its slow as $hit

Second, its horrible on gas mileage

Third, gas seems to be making its way into the oil

Fourth, No matter what i do i cant get the tach to work with the VW distro. I can get it to read a signal but the needle flutters around like crazy(within 1500rpms of actual speed) And i tried a tach/dwell meter tuner tool and also a sunpro tach i had laying around and they give a clean reading without the needle fluttering, any ideas??

The car idles amazing, revs up good, has no dead spots. It never misfires, not even a little sputter here and there.

The plugs arnt black, pretty white. So if anything i may be running lean. So why such bad gas mileage? Also i mentioned the oil smells like gas, could it be getting past the rings? If that were the case wouldnt it burn oil? (which it dosent)

I have straight pipes on it but i stuck a muffler on it with baffles so its got back pressure.

i adjusted cam timing 6 degrees advance to compensate for the head milling (.060)

ignition timing is 12 degrees, i need to check full advance but gotta get ahold of a advance-able timing light.

I put it to the floor on some back roads and would go 80mph and struggle to keep going, my stock TBI will pull consistently to 100mph, and so did this car before i messed with it.

I havent gotten around to any shift mods yet but the trans seems to shift nicely and feels healthy.

Anyone have any ideas on what can be going on with my car? Its slower than it was :0
 
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