FTbaba

Hey hondatech,

I am in the process of rebuilding the engine in my 1991 prelude si 4ws. I've decided to turbo it but have never boosted anything before. I've owned a gti in the past and miss the torque and sounds. I need some help on what to use. Any feedback or help is greatly appreciated. Car will be used as a daily/autox.

b21a1 (2.1L) Has FRM sleeves
Stock 140hp 135tq
2056cc
Compression 9.4:1
-PK3 OBD1 ECU
-Max psi on map sensor is 11.2
-6500 redline

-Motor is out and I am rebuilding it (OEM rings, gaskets, bearings,head bolts,etc)
-Goals are 200whp and more torque than the gti which was around 180.
-Would also like a quick spool time

.
So far I have
-Unknown Boost gauge from GTI
-Unknown BOV from GTI
-OBX LSD (Plan on getting new bolts/washers)

What I plan on installing
-Ebay Cast iron H22 Log Manifold
-Ebay intercooler and piping
-Twisted motion Turbo Twisted Motion T3 T4 T04E Quick Spool Turbo Civic B18 B16 B20 Honda USA Made | eBay
-450cc injectors
-255 LPH Pump
-t fitting, oil lines,etc.
-not sure on exhaust or wastegate set-up yet

Questions:
-Can I chip/tune a PK3 ECU? (was thinking about sending to phearable and get a base map for 89$)
-Do I need a better clutch for 200whp 180tq? (The one I have grabs pretty good)
-Are the oem rods safe?
-Is that turbo too much for 200whp? Would it spool quickly?
-Another option is 1g and 2g eclipses. I can swap manifolds,injectors,pump,intercooler. But the turbos are 14b and t25. Would these be too small for my goal? This would probably be the cheapest route if I can find a wrecked/blown one.

king06

iTrader: (1)

Bad motor to start with. Why do you have an h22 manifold?

read this

Turbo Charging 88-91 Preludes | HondaSwap

2kdrift

ebay turbo just say no, and a t25 would be more suited to your power goals anyway

FTbaba

Well I do have a b20a5 block with iron sleeves that I could swap but then I just bought rings,bearings, etc. rebuild parts for the b21a1. I could do b21a1 head on the b20a5 block and lower the compression. I don't know if that is a good thing though. Supposedly if you change the oil every 2500-3000 the b21a1 don't burn a drop of oil, it is the ones that get abused that burn oil. My car has 189,000 miles on it. H22 manifold because nobody makes manifolds for b21a1/b20a5 and this guy got it to work Some very cool pictures of my summer build - Honda Prelude Forum : Honda Prelude Forums

And I have heard ebay turbos are bad but that turbo says it is assembled in the US and they check the bearings and clearances? And are you sure a t25 would be good? There's a few people on the prelude forums making low power with them;

CADster's formerly Bgerk's Setup:
www.LSDMotorsports.com - Manifold Kit(DIY) I had welded togther
Intercooler and Piping
Rebuilt and Polished 14b
Polished DSM BOV
Downpipe
SAFC II- for Tuning
Wired-up MSD-BTM - for Tuning
GM 2-Bar map sensor
walbro 255lph fule pump
modified Powersteering line to go over and down on the driverside
Zex Plugs
*Kept all A/C, Powersteering, Cruise Control.
Power Output:
158 w.h.p and 159 torque - Dynoed @ 8psi

Schister66

Way too small. Pick this instead. Its small, name-brand (not eBay ****) and since it's T3 flanged, not some goofy DSM nonsense, it'll fit most manifolds.

Garrett GT28 Journal Bearing

Still crap. You're just throwing away money.

gc8dc95

Have the b20a5 bored to fit the b21 pistons.
You can't chip the prelude ecu. Buy a chipped p06 or similar.
Have you checked prelude power.com?

I used to have a 400+whp 3g prelude. Ask away.

FTbaba

Thanks for the replies. Boring the b20a5 to b21a1 specs sounds good. How much HP could I make reliably? So technically for the ECU I could just plug this in to my harness, Chipped OBD1 Non-VTEC ECU with Custom Basemap Chip Package , take it to my tuner and they can tune it?

Yeah I have a preludepower account but figured I would get a quicker response here. 865$ is pretty expensive. I really would like to spend 500-600$ max on a turbo, but might be able to find one used.

Also in this turbo install thread, https://honda-tech.com/forums/forced...speed-1263795/, the guy uses a 3bar map sensor. Do I need a better one than stock? And does my car have a resistor box? do I need one?

2kdrift

IMO $900 is not expensive not when you look at the big picture....you will easily spend 4k on a DECENT turbo setup....not even including clutch, tires, suspension, rebuilding motor etc. so an extra 200-300 is nothing. DO it right the first time. Lets just say every turbo in the world will fail sooner or later...so why by used or chinese crap. Better off in the long run getting something you know the history of. If your getting it from a friend or something like that and you know the history sure, other then that its a gamble on how much life it has left

gc8dc95

Yes any chipped obd1 ecu will be fine.

You only need the 3bar if you are going to exceed the 11psi of boost threshold.

The very first turbo I put on my lude was a 14b and it actually matched the power range quite well. These motors are a bit different having more stroke, but lesser flowing heads. You can make 200 whp with it.

Yes, your car has a resistor box. You may or may not need to keep it based on the injector type you buy.

Schister66

This is true; HOWEVER, if you tune on the stock MAP sensor at 10psi and then decide you want to go to 15psi (and need a 3bar/4bar), the scaling on the two sensors is different and the tune will require some rework (@ $150+/hr). You're honestly better off getting a MAP sensor up front and not worrying about it any further

2kdrift

I remember seeing a post from phearable or something...talking about getting a larger map sensor so that boost cut can be properly dialed in so it makes sense to have at least a few PSI headroom, 3/4 bar maps are pretty cheap IMO not really any reason not to get one

TheShodan

iTrader: (14)

that's because consumer logic typically purchase larger turbochargers than what meets specific needs. I've never found the need of a 4bar map unless the purpose was intentionally over 30psi for 600whp+. Of course, I only get sensors from the OEM manufacturers and not aftermarket companies in which consistency of electronics (good or bad) may cause symptoms and issues that cause undesirable effects.

2kdrift

ahhh Im on a 3 Bar myself, which gives me a decent amount of head room, I have the ability to turn the boost up in the future if needed, a 2 bar would not have worked at all at my boost levels

FTbaba

Thanks for the replies.

Is there much difference between these two turbos? Gt28 vs T3/T4 60 trim?
Garrett GT28 Journal Bearing
vs
GO-AUTOWORKs Garrett T3/T4 60 trim

Schister66

Yes, the GT28 is going to spool up quicker and since it'll support 350whp or so, it'll easily meet your needs. The t3/t04e 60 trim is capable of making upper 400's. It'll be laggier than the GT28

Basically you're capped on power and both turbos will make your goal easily. Get the smaller of the two (GT28)

FTbaba

Thanks for the info! I will probably go with the gt28 unless I find something cheaper/used.


-How much hp or psi can I run reliably on a b20a5 bored out to a b21a1?
-I have a normal head gasket, do I need a MLS one? They are about 90$.


Still need to figure out exhaust setup ( 2.5 or 3"), clutch, flywheel, wastegate and how to control the boost. Might need a smaller radiator. Still researching this stuff but if anybody has any recommendations.

gc8dc95

Daily driver 300hp.

I would highly recommend the MLS gasket, as these have a poor reputation. In fact the only engine issue ever head was a blown headgasket. I was part of the original group to get MLS gaskets and it made a big difference.

Iran a Spec clutch, stock flywheel, Tial wastegate, Neukin 1/2 radiator, 3" exhaust

gc8dc95

Daily driver 300hp.

I would highly recommend the MLS gasket, as the oem have a poor reputation. In fact the only engine issue ever head was a blown headgasket. I was part of the original group to get MLS gaskets and it made a big difference.

Iran a Spec clutch, stock flywheel, Tial wastegate, Neukin 1/2 radiator, 3" exhaust

P.L.F.Y 575

I have 440CC RC injectors for sell. Used them in a daily for about six months. There is nothing wrong with them just started a new setup $300 if you are interested or know anyone who would be.

FTbaba

Thanks for the offer but trying to keep injectors under 140$.

Do you think it would be better to put the b21a1 head on the b20a5 block without boring it? I can always return the 83mm b21a1 piston rings and get some 81mm b20a5. And then I think I can use the same bearings.

Also here is some pictures;

motoxxxman

you are definitely better off boring the b20a5 block to fit the b21 pistons, and using the b21 top end. don't worry about block strength. even bored to 83mm, your weakest links are the rods and pistons. I'm not sure how much power the stock rods can hold reliably, I'm guessing 225 or so. the stock pistons i can definitely say are good to about 250, at which point they start shattering ringlands like clockwork.

if you're nervous about boring the a5 block, know this: I'm just shy of 400whp/400tq on mine right now, I run a b20a5 block bored to 83.5mm (NOT sleeved). zero issues after years of daily abuse.

also, don't bother with a modified manifold for a different motor. it will not work as well as you think. find Christopher Thomas on facebook and send him a message. he still makes manifolds for our cars, in several different styles and prices. you can also find Zemfira Razamanova on facebook, he currently is selling several manifolds and other turbo parts for our cars

FTbaba

Thanks for the info. Ill check them out. Also i just picked up a 50trim .63a/r turbonetics turbo.