420a Build Suggestions

[fornstar13]

Hey Everyone. I have a '97 Avenger with the 420a 2.0 and a 5speed. The car has 172,000 on it and shows. The body has been redone last year, bodykit and fresh paint. Now this summer i would like to make it go along with the show. I plan on an NA build for simplicity and less to worry about later down the road. Anyways i visited a site called Modern Performance Racing Products and they have a nice all around bottom end rebuild kit. I would like to get the 10.5:1 compression pistons. Is this a wise choice. Im not looking for huge power. Just in the 230whp range. Umm I was also lokking at there topend rebuild kit but personally think that is a little high. I planned on the cams though and lifters, etc. along with an entire gasket kit. Any suggestions are welcome as I am new to an engine rebuild. I plan on having the block acid rinsed and bored .20 over and then have an engine technician assemble it because i dont trust myself with it. Are there any other things i need? Like fuel upgrade? I wanted to get the engine together and run it for awhile as is and then upgrade the exhaust and intake. What would be a good diameter tb for my build? thanks in advance
FornStar

 

[adammethner05]

I would advise setting your NA sights a little bit lower unless you're looking to pump a ton of money into your engine. Mark Bullett has the fastest/most powerful NA 420a and he's pushing just over 200whp.

10.5 compression is pretty good for NA, but it will also help out down the road if you ever decide to go turbo. Not too high, not too low.

For the intake manifold, it's usually best to just port the stocker. As for the throttle body, you could have the stock one ported, or purchase a 57mm or 60mm online. There's always the Jeep 60mm mod, but there's a few things that need to be changed to use it.

Air intake, just go with a short ram.

Check out 2GNT.com - home, this site contains the information required to do just about anything you want to your NA motor.

 

[fornstar13]

Srry i meant 230 at the crank but idk what that would translate to the wheels. Anyone know what sort of clutch would work for this. I don't think i need anything too aggressive but i would like it to grab when i line up next to my friends. One has a 3.8l mustang and the other a 3.8l camaro. So i would like to show them a "domestic" can achieve quickness, look good but not ricey and still get great gas milage. What are things i should check/ replace while the engine is out of the car? Such as trans fluid? cv joints? vacuum hoses? things like that. I just want to get as much knowlegde as i can before i do the build this summer. i don't want to be midproject and realise i need to order some part ### this one is about to sh!t the bed. Thanx in return
FornStaR

 

[rstare]

Srry i meant 230 at the crank but idk what that would translate to the wheels. Anyone know what sort of clutch would work for this. I don't think i need anything too aggressive but i would like it to grab when i line up next to my friends. One has a 3.8l mustang and the other a 3.8l camaro. So i would like to show them a "domestic" can achieve quickness, look good but not ricey and still get great gas milage. What are things i should check/ replace while the engine is out of the car? Such as trans fluid? cv joints? vacuum hoses? things like that. I just want to get as much knowlegde as i can before i do the build this summer. i don't want to be midproject and realise i need to order some part ### this one is about to sh!t the bed. Thanx in return
FornStaR

You should do all the routine maintenance prior to modding. Make sure it has no leaks, change the gaskets, timing belt.. ect. Working on the car is the best way to learning everything about it, so thats what I would start doing. 230 crank hp is going to put you at around 200whp. So if you really want to go N/A be ready to spend alllloot of money. 12.5:1 compression not 10.5:1. And it wont be able to be a daily driver. Bullets n/a idles like, barley I guess, . So honestly you might what to consider going turbo.

Edit: Southbend clutches are the clutch of choice around here.

 

[BigRand]

Honestly, if NA power is the way you want to go, your going to have to be thinking a little different than some of the domsetic guys (unless they are running computers on their V8's as well)

Megasquirt, is probably the only real way your going to be able to tune any of the mods (top end botttom end) to really see any of the true gains.

I guess if I was in your position "again" and I really wanted to go NA first, I'd start with the top end rebuild. Ported intake manifold, Throttle body (size is still TBD or argued later), Head ported and polished agressively, oversized valves, retainers, and rockers, and a stage 2 cam set.

With megasquirt, and FPR, wideband and some other sensors and injectors, you can throw some fuel at it along with some ignition timing, and see what you get.
If its not what you like and you want to go turbo, your basically ready to just pop in some bigger injectors, turbo parts, and turbo specific bottom end and your set to run 15-20psi, with your top end complete.

I don't know thats if you change your mind I guess. Your best person to ask about NA mods is Bulletdsm.

 

[fornstar13]

So this project for me has to be streetable and affordable a I guess idk what kindof power i was looking for. I planned on doing the bottom end as an "upgraded" rebuild as i plan to keep this car and don't trust stock internals with 170,000 miles on it. I don't want any higher then 10.5:1 compression for mpg reasons. I want my avenger to pull like a v6 or little stronger, thats it . And I dont want to go wild with the porting or bore of my intake manifold. I planned on boring the tb, but is boring the stock manifold neccassy, is it that helpful. I need this to still pass emissions so would aftermarket cams still allow me to do that. I nearly didn't pass this year because i kept tripping a PO1204 and if anyone knows what that is its a pain in the ass to trace. So like any other person who refuses to pay $80 an hour i painstakingly went through all the vacuum line with tb cleaner, along with gaskets. Turned out to be my pcv valve, don't ask me how i figured it out but i did . So umm, what im asking is for a good "stage 1.5" over haul kit for my engine. But i didn't like the price of modern performance's topend kit. I do however like their bottom end kit. I hate being a pain in the a$$ but this is what i want for my car. Thank You

 

[rstare]

Imo, rebuild the bottom end with lower compression forged internals and turbo it. Unless your absolutly set on going N/A. Your not going to make nearly the same power N/A as turbo.

 

[fornstar13]

well what kinda price and power would be associated with a turbokit? Exhuast mainfold? turbo size ? what intercooler to use? i need sumthing for my map sensor right? whats the o2 wideband? Does it measure the steichiometric ratio or is it sumthing else. I was thinking a turbo initially but have heard of ppl running into problems with masking the boost from the map sensor. Thanks
FornStar

 

[rstare]

well what kinda price and power would be associated with a turbokit?

Turbo kit, peiecing it together yourself will generally cost around $2k, (estimate). You can do it for cheaper, or you can go all out. This is with a cast log manifold and a cheaper, or used turbo.
With a basic 12:1 fmu and 8psi of boost you will be looking at around 225whp. (Hahns says 250-275 crank hp)

Exhuast mainfold? turbo size ? what intercooler to use?

Things you will need are, turbo (the size is really only a decision you can make, most people use a t3/t4 of some sort), exhaust manifold, wastegate, intercooler and the piping(either get a ebay fmic, or look on like CImotorsports, the piping is best and cheapest when you get it custom made), blow off valve, some type of fuel setup. (Most people running only 8psi use a 12:1 fmu, which raises your fuel pressure 12psi for every 1psi of boost, using a 12:1 fmu allows you to use stock injectors) And a 255lph hp fuel pump to go along with. You will also most likley need to have your downpipe custom made.

whats the o2 wideband? Does it measure the steichiometric ratio or is it sumthing else.

Yes a wideband tells you your afr (air to fuel raito) The stichometric refers to when the afr is a perfect ratio and the two balance out, this is 14.7:1. So when combustion occurs with 14.7 parts air to 1 part fuel that is when you have as close to possible as a "emissionless" combustion. At cruising speeds is when the ecu tries to implicate 14.7:1. Most of the time its richer though.

i need sumthing for my map sensor right?

I was thinking a turbo initially but have heard of ppl running into problems with masking the boost from the map sensor.

The Map sensor puts out a certian voltage for the pressue in the intake manifold. 4.56v I believe is when the pressure is at 0psi, meaning you have WOT on a N/A car. (Dont quote me on the voltage though). Once you introduce boost the map will put out more then 4.56v to the ecu and then the ecu will start to cut fuel. So a FCD, basically a voltage clamp is the solution for this. With a fcd the ecu doesnt even know boost is occuring, it just thinks your at WOT. There is also a missing link which is a mechanical solution, but most of the time it just doesnt work. Go to Symtechlabs.com and get their FCD, imo.

Sorry for the length, just wanted to answer all your question and have no confusion.

 

[fornstar13]

Thanks for the info. One last question I hope. What do i do for oil? Tap into the oil pan or is there an external oil line i can tap into? I still need to run a return into the oil pan though right? I was leaning away from a turbo because of this. I can just see it one day on the highway cruising and i blow a bead out on the oil pan return line and then im stranded. Idk just my main concern i guess is reliable power. I have quite alot of fabricating friends and I can do quite alot myself so the build im not too worried about. Its things like mentioned above. And maybe an electrical malfuction such as the map sensor. Let me know ### you think. Thanks again
FornStar

 

[rstare]

What do i do for oil? Tap into the oil pan or is there an external oil line i can tap into? I still need to run a return into the oil pan though right? I was leaning away from a turbo because of this.

For oil feed, you can just tap into where the oil pressure sending unit is. Its a lime green plug on the back of the block with a 3/8" npt on it. Just get a 3/8" tee, and then tap into the oil feed line there.
For the oil return you have two options, I think it is OBX that makes a 420a oil pan with a bung welded into it, but its like $200. What I did was get a steel -10an bung and just weld it onto the oil pan.
http://www.dsmtuners.com/forums/420a-bolt-tech/302228-oil-pan-tapping-location.html
That thread will show you the right location to tap it in at.

Idk just my main concern i guess is reliable power.

There are lots of people that turbo their 420a's and use them as daily drivers.

And maybe an electrical malfuction such as the map sensor.

The FCD will do fine for that, I have never heard of one malfuntioning in anyway. Unlike the missing link, where there are multiple stories.

 

[99RedGs]

If you don't want to spend the money on a turbo build my suggestion is:

10.5:1 wiseco pistons
Cams ( you can figure out what you'll need)
Eagle rods
Stock bearings
MSnS (Megasquirt xtra)
100+ wet shot
Southbend clutch (Choose what fits your needs)
2.5" mandrel bent piping
4-1 header or the equivilant


You should be fine leaving the head stock and just adding cams. It flows very well in stock form. Odds are the head is in good shape as well and you can get away with a cleaning and not have to spend money on a rebuild yet.This type of build would probably end up far cheaper than a turbo build, better chance to pass emmissions (don't quote me on this though), still maintain good mpg, give you good power when using nitrous (~ 200 whp which was your goal), and be plenty of fun to drive. Also with 10.5:1 you can get away with turbo later if you decide you want that route and you will already be half way there.

just my .02 though

Personally I'm building for turbo and low comp (low comp because I don't trust my tuning capabilities yet). I think always having the power there vs having to have a bottle and turn it on is a better option. Also depending on how often you use your N2O it will add up to the price of a turbo set-up in the end. Oh, and I don't have to worry about emissions here so f#@k the environment

 

[fornstar13]

Thanks 99redgs and all others. These are the answer i can't get around here u've been a big help. 99redgs consider urself lucky, but emissions aren't that hard to pass as long as ## evap system is working and everything else is up to par u'll pass. Idk with my year (97) im allowed to have 2 monitors not set. So as long as everything else is working i don't need my cat. Lol seems like a failed system and i think thats why they changed it in 2000 to only 1 monitor. But yea emissions is still a PITA, unless u have a scantool. And i don't plan on buying one for the minimum ammount of emission repair that i do. Anyway im rambling so i bid u good day thanks again.
FornStar

 

[99RedGs]

Thanks 99redgs and all others. These are the answer i can't get around here u've been a big help. 99redgs consider urself lucky, but emissions aren't that hard to pass as long as ## evap system is working and everything else is up to par u'll pass. Idk with my year (97) im allowed to have 2 monitors not set. So as long as everything else is working i don't need my cat. Lol seems like a failed system and i think thats why they changed it in 2000 to only 1 monitor. But yea emissions is still a PITA, unless u have a scantool. And i don't plan on buying one for the minimum ammount of emission repair that i do. Anyway im rambling so i bid u good day thanks again.
FornStar

Checkauto / advanced auto allow you to rent their scan tool for free.. Just a heads up

 

[fornstar13]

Another thing If i do the turbo build. I would have to increase the amount of oil during an oil change right? Would it be wise to change viscocity as well? What brand of oil/filter do you use? Just a dailydriver with an occasitional race maybe once every 2 months during the summer. I don't mean to be a pain with all these questions but im having a hard time deciding what i want. Either go with a turbo now or do a basic na build with eagle rods, 10.5 pistons, bore my tb and finish with header and intake. But with the NA i might want more power . Idk, im glad that i don't have to decide until this summer. I guess the a turbo would be the wise build with a cast exhaust manifold and ebay fmic. Are there silicone couplings reliable under boost? How does the intercooler stay in the front would i have to fab a bracket? Alright im done asking. Thanks

 

[fornstar13]

Is it a good one because i have the cheap one in my garage. I want a genesis but they are like $2000 last time i checked.

 

[rstare]

I would have to increase the amount of oil during an oil change right? Would it be wise to change viscocity as well? What brand of oil/filter do you use?

No, you wont have to increase amount of oil, 5w30 (which is probably what you use now), and I get fram ph16 or tg16, I hear tg is better, I doubt it matters much.

Are there silicone couplings reliable under boost? How does the intercooler stay in the front would i have to fab a bracket?

Yup, go with silicone couplers, plastic stuff is just going blow. If you got a ebay fmic you would have to make brackets.
2GNT.com - Custom_eBay_IC_Install_with_Pipe_Routing
Thats a link to a ebay fmic install walkthrough.
You could go with a Hahn or star fmic. They both pretty much mount up. Star fmic is small, and I personally dont like it (I havent had any experience with it though) I bought the Hahn fmic, just because, well its freaking massive, mounts right up, nice and easy, and its efficent. But its also more expensive.

Is it a good one because i have the cheap one in my garage. I want a genesis but they are like $2000 last time i checked.

And Im not sure what your talking about here at all....

 

[fornstar13]

Is the hahn fmic the one thats in your profile pic? I also wonder how well an intercooler of that size or even the ebay one will fit on the front of my avenger. I know theres room on the bottom but where it contours back ir where im worried it will hit. Thanks
FornStar

 

[rstare]

Yup thats the Hahns fmic.
http://www.dsmtuners.com/forums/420a-bolt-tech/302355-turbo-build-3.html
Thats the thread for my build, theres a bunch of pics of it in there.
Call Hahns, and ask them if they have tried putting it on a avenger, or look for someone on here with a avenger and see what fmic there using.

 

[fornstar13]

theres another guy with a gsx avenger hybrid. But he has a different bumper cover and looks to be a smaller intercooler. I really like the sound of a treadstone turbo kit. It looks clean and compact. Whats ## thoughts? Thanks

 

[rstare]

The treadstone kit is cheaper and not as well put together as Hahns. It has a 1 page instruction manual while Hahns kit has a 57pg manual I believe it is? Someone with a Hahn kit correct me if I am wrong. Either way you get the idea.
Both kits can be peieced together for less then they sell for though, and plus that way you wont be replacing parts from either kits that werent exactly what you wanted. Such as the cartech fmu with the Hahn kit. Its not really recommended because alot of people have had bad experience with it.

 

[fornstar13]

I like the turbo and the fmic and piping. Shiny . Turbonetics are good turbos, right? I was looking at
t3, t4, and t3/t4 hybrids. It looks to me like the hybrids have a smaller diameter opening, is this to help keep lag down? Let me get this straight, I would require fcd and an fmu? What is a s-fac? And if I were to decide to go the turbo route would you suggest the 8.8:1 pistons over the 10.5:1, would i need a different headgasket. What kind of boost pressure could i expect from a t3/t4 build similar to the treadstone kit? Thanks again for being responsive to my questions.

 

[99RedGs]

I like the turbo and the fmic and piping. Shiny . Turbonetics are good turbos, right? I was looking at
t3, t4, and t3/t4 hybrids. It looks to me like the hybrids have a smaller diameter opening, is this to help keep lag down? Let me get this straight, I would require fcd and an fmu? What is a s-fac? And if I were to decide to go the turbo route would you suggest the 8.8:1 pistons over the 10.5:1, would i need a different headgasket. What kind of boost pressure could i expect from a t3/t4 build similar to the treadstone kit? Thanks again for being responsive to my questions.

I don't know specifically about Turbonetics, but I will say don't buy a turbo off ebay unless you feel like taking a gamble. Sometimes they are good and workout, sometimes they blow in 200 miles. Its your choice if you feel like taking the chance.

Safc is a piggyback tuning device that really doesn't work too well with our cars when they are turbo. In short it really only works for helping idle and doesn't really do much when you are in boost. I would say don't bother with it. (Obviously there are exceptions, but this is the simplest answer for you)

8.8:1 will allow you to run more boost without knocking and is usually used because it helps especially if you are an inexperienced tuner. 10.5:1 will basically take less boost to run the same power as a low compression motor but you have a higher chance of knocking. Personally, like most people, I am going with 8.8:1 for what its worth.

T3/T3 isn't exactly the size of the turbo, but I'll just say if you have forged rods, forged pistons, and good fuel management you can run as much boost as your heart desires. This is of course assuming you tune accordingly. I'm not a turbo expert so I can't make an informed comment on the differences between T3,T4, and T#/T4 hybrid turbos. From what I understand T3's usually sppol faster than T4's, and T3/T4 hybrids spool somewhere in the middle of the two. Spool is dependent on inducer and exducer sizes from what I understand.

Yes, you will need a FCD and a FMU. They are two different things. The FCD will prevent fuel cut because we have a speed density set-up, and the FMU will raise the fuel pressure according to the amount of boost you are running.

 

[rstare]

Turbonetics are good turbos, right?

I hear good and I hear bad. But I know they will fix the turbo most of the time, if it breaks down somehow.

It looks to me like the hybrids have a smaller diameter opening, is this to help keep lag down?

Im turbo physics expert, but I believe lag is more related to the size of the turbine blades. Obviously a larger diameter of turbine blades is going to take more exhaust gas to spool it up, therefore creating lag. So the size of the compressor inlet which I believe is what you are referring to doesnt have much to do with lag.

Let me get this straight, I would require fcd and an fmu?

A fcd (Fuel cut defender) is to stop the ecu from seeing boost. (If the ecu sees boost it cuts fuel)
A fmu (fuel managment unit) is used to raise fuel pressure.
Let me explain.
Under N/A conditions their is always 53psi of fuel pressure. As rpms increase the ecu controls the injector pulse width.
Now that there is boost you need more fuel, but because of the fcd the ecu doesnt know there is boost, it injects fuel as if you are N/A. So your not getting enough fuel. So there is one other way to get more fuel into the cylinders other then controlling the pulse. Raise the fuel pressure. This is exactly what the fmu does. Most people get a 12:1 fmu. So for every one pound of boost it raises your fuel pressure 12psi. That way your getting enough fuel into the combustion chamber to account for the boost.
I think I covered it, if theres something you dont get let me know.

What is a s-fac?

Super air flow converter. Basically it taps into your MAF allowing you to control fuel. We dont have a MAF though, so its taps into the Map sensor. Only problem is the voltage clamp. So its not a very good solution for the 420a. I highly dont suggest it. Search around for it on here, and there are very good explainations of why its not the best.

And if I were to decide to go the turbo route would you suggest the 8.8:1 pistons over the 10.5:1, would i need a different headgasket.

8.8:1 pistons is the way to go for turbo. Reduces chance of knock.. If your rebuilding the bottom end you might as well get a mls (multi layer steel) headgasket.

What kind of boost pressure could i expect from a t3/t4 build similar to the treadstone kit?

I believe the treadstone kit comes with a 8psi wastegate spring.

If you build your bottom end you can handle plenty of boost. The only thing holding you back will be your fuel setup and timing.
A 12:1 fmu is only good for 8psi. A sfmu and bigger injectors should allow you to get up around 16psi (I wouldnt recommend it though, due to timing). And if you can pull timing then the sky is the limit. But I really wouldnt suggest going over 12psi if you are not pulling timing.
Alot of people dont pull timing and run 16psi they say they dont hear knock, but give it time they will see. Like 1slow97. Ran 19psi will portfueler which is a 8 injector setup, didnt pull timing and it ran fine for a little while. Then knock took out his motor. So just a heads up.

Agian sorry this is long. I just like to answer in detail so you dont have a million different things your questioning. I like to know how and why things work, so thats the way I tell people to.

 

[fornstar13]

Thanks for all that info. What type of fmu and fcd would you suggest? I think I will compile my own setup like you suggested using the treadstone kit as a guideline. I really like their fmic like I said earlier so i might buy that from them along with the downpipe kit. Yeah i definatly wouldn't cheap out and buy an ebay turbo . I don't have use for a $200 paper weight. Can I clean my injectors or should I buy new ones? Do you guys run a seperate inline fuel filter? Will my stock fuel pump hold up to the demand of the fmu or will I need a different one? I plan on only 8psi. So the ecu controls fuel trim but does it also control pressure? Is there still a mechanical fuel pressure regulator? 12:1 wouldn't that equate to 149psi at the full 8psi of boost. Sounds like alot will my fuel lines take this? Well I think those are all the questions floating around in my head . Thanks again.
FornStar