The cheap & cheerful SR20DE+T guide

[BenRice]

This is a guide to show the tools, parts and process for turbo charging an SR20DE on a budget. I've just done this on a car that survived a day and a half of solid drifting so time to share it all with you

The full process is documented visually on my IG highlights: https://www.instagram.com/unclebensriceballs/

If you want to be critical or tell me it won't work, message me directly or piss off. I don't want this thread filled with "you NEED a standalone", "you NEED oil squirters", "you NEED to pull the engine out". If you disagree, do your own guide

Specialist tools needed:

- Tap the same thread pitch as your chosen oil drain block fitting. I used a stock DET block fitting which is 1/2" BSPT (and 5/8" hose barb)
- Drill for above tap. I used a 23/32" drill bit which was perfect for the ½” BSPT tap
- Compressor (air mattress inflator is ideal)
- Timing light

Now the parts:

- Turbo manifold (factory cast is fine)
- Turbo (up to you, but factory T25G / T28 is cheapest. Will need the compressor inlet & outlet elbows and oil drain pipe)
- Dump pipe (bigger is better, factory will do if you really are on a tight budget)
- Larger exhaust (3" is best, 2.5" is passable, don't use stock DE while tuning, get M18x1.5 bung fitted to front pipe for wideband)
- T-fitting to go where factory oil pressure sensor for oil feed (or add an oil sandwich plate and run oil feed off there)
- 1m braided oil feed with fittings to suit T piece & chosen turbo
- Oil drain block fitting (again, factory is ½” BSPT and 5/8” barb)
- Intercooler & piping (generic FMIC or go DIY midmount as described later)
- Turbo intake piping (we made one out of random 2” joiners & pipes)
- Bigger injectors (we just used factory DET 370cc injectors still in a factory rail)
- Rising rate FPR (we fitted an adjustable Tomei one as we didn’t know if we need to bump up base fuel pressure, but we didn’t so factory DET would be fine)
- Walbro 255 fuel pump (or better)
- VAFC2/SAFC2 or newer (will go into more depth on why later)
- Wideband & boost gauges (don’t bother tuning without them. If you're lucky you can borrow them)

Consumables:

- New gaskets (multilayer exh manifold, T2, exh dump pipe, 3 bolt)
- 16mm oil drain hose & clamps
- Oil & filter x2
- Fuel filter
- 4mm vacuum hose

Optional parts (in order of importance):

- Oil pressure & water temp gauges
- Heavier clutch
- Alloy radiator
- Battery relocation / smaller battery
- Oil catch can
- External oil cooler

Next, the process

 

[BenRice]

We started by fitting the intercooler and swapping the fuel pump. I’ll do a separate thread for a DIY mid mount intercooler. And there are plenty of guides on how to swap a fuel pump so am not going to bother


Fit VAFC
a. Remove trim pieces and unbolt ECU

b. Identify using Apexi diagrams which wires you want to splice into and label them

c. Hook up power & ground to the VAFC, and if secondhand, reset to base settings once it powers up
d. Hook up remainder of sensor wires and check they work

e. Tidy up harness and put ECU away again
f. Set the RPM points (NE Points)
g. Make sure all the Correction Factors are 0
h. Set Throttle Points
.......i. Lo: 20%
.......ii. High: 70%
i. Set Sensor Number to 6 in/6 out
j. Start and make sure car ran as it did. If not, double check your wiring

Remove plenum & swap injectors
a. Start car and while running pull fuel pump fuse and let engine die
b. Unhook the battery & remove
c. Put fuel pump fuse back in
d. Remove DE intake
e. Remove throttle cable from throttle body and unbolt throttle cable mount (keep on throttle cable) and move cable out of the way
f. Unplug plugs for & around IACV and earths
g. Remove 2x brackets between plenum and head (14mm headed bolts)
h. Unbolt throttle body and let it hang down
i. Unhook booster vacuum line & PCV hose
j. Undo ground strap
k. Unbolt & remove top half of plenum

l. Unclip the injectors plugs
m. Remove fuel lines off fuel rail
.......i. If you are reusing your injector rail, stop here and undo the injector hats
.......ii. Twist injector 90deg so plug is next to a hat bolt hole
.......iii. Use flat head screw driver in the recess under the plug to pry out
.......iv. Fit DET injectors & FPR with your choice of lubricant (use lots. I used engine oil)
.......v. Refit injector hats and replace Philips head bolts with hex-headed M5 bolts
n. Undo the 3x bolts holding the rail down
o. Remove injector rail, watching out for the collars around the injectors
p. Fit new injector rail with larger injectors
q. Hook up fuel lines (make sure to remove restrictor pellet in feed hose)
r. Swap fuel filter
s. Cap the PCV ports on the plenum & rocker cover

t. Refit everything

VAFC settings
a. Refit & hook up battery
b. Set all Narrow throttle correction factors to -15% (if using 370cc injectors, otherwise tailor to whatever injectors you use targeting 14:1 as it's only low throttle)
b. Start car and test

Remove exhaust
a. Soak the manifold & any flange bolts in penetrating lubricant to avoid cracking studs

b. Remove manifold

c. Tape off ports

Drill & tap block for oil drain
a. Centre punch the casting of the block where the oil drain is on a DET

b. Drill pilot hole 40mm into block

c. Drill 23/32” drill bit 40mm into block

d. Hook inflator up to rocker cover port (middle on exhaust side)
e. Grease end of drill bit and drill final 10mm (clean off shavings regularly)

f. Once drilling is done air will come out the hole, throwing shavings at you

g. Tap hole (put grease on tap to catch shavings, keep inflator going)

h. Once tapping done turn off inflator
i. Run finger around inside of hole to get any shavings that dropped through
j. Drain oil (make sure engine is level) and fit block fitting

k. Pour petrol through fitting and into engine to flush out any more shavings
l. Open up oil cap and let petrol evaporate

Oil feed
a. Remove intake manifold brace
b. Remove factory oil pressure sensor (very hard to do, if fitting aftermarket oil pressure gauge then smash plug, remove sensor with socket and throw it away)
c. Fit T-piece into engine
d. Fit oil pressure sensor

e. Fit oil feed line

f. Run oil feed line under car, next to steering rack (cable tie line to steering rack / subframe)
g. Refit oil drain bung and refill with oil

Fit turbo manifold, turbo & dump pipe
a. Clean off old gasket & fit multilayer manifold-block gasket

b. Fit turbo to manifold
c. Fit dump pipe to turbo (and O2 sensor)
d. Put manifold/turbo/dump pipe on the LHS chassis rail and fit oil feed
e. Slide manifold on and fit nuts

f. Fit oil drain pipe gasket, pipe & hose

Fit exhaust
a. Fit front pipe & exhaust

b. Fit wideband sensor to bung in front pipe

Fit turbo intake & catch can
a. Either use factory rubber intake hose or make it DIY from 2” joiners & pipe and fit AFM to this
b. Fit catch can and run middle exhaust-side rocker cover port to one side and the other to the turbo intake / filter

Hook up intercooler
a. Connect hot side (compressor to intercooler) pipe
b. Connect wastegate port to charge pipe (port on compressor or intercooler hot side)

Plugs, timing & wideband
a. Stock are 6’s, 7’s are ideal. Gap to 0.8mm
b. Stock is 15deg BTDC. We retarded it to 10deg BTDC which was too much. We're going to retune on 12-13 deg
c. Wire in 12V feed (with 5A inline fuse) and ground to wideband and connect to sensor

Tune (will do a separate post for this)
a. Start correction factors at -7% on Wide Throttle map if on 370cc injectors and fine tune from there.
b. Aim for between 10.0 and 12.0 air/fuel on full throttle map(s)
c. Bring correction factor up to 0% for 7000+ rpm points to give extra fuel on limiter

Change oil & filter

 

[BenRice]

Why the VAFC?

The early SAFC had 8 rpm points you could adjust the correction factor (ie airflow signal) at. The SAFC2 & SAFC NEO have 12.

The VAFC and VAFC2 have 12 on the Low Cam map and another 12 on the High Cam map, so 24 in total! More rpm points the finer the tuning can be.

The silver top SR20DE has a rev limit of 7200. Most Honda's rev A LOT higher. 24 rpm points from 1000 to 7200 = VERY fine tuning (for an AFC that is)


Settings:

I set the "VTEC" switch rpm to be 5700 - the factory rpm that VCT is switched off on a silver top. I also did 100rpm increments for 3 rpm points either side to see if there was any fluctuations in air/fuel at the switch over. I also set the last 3 rpm points to be 7000, 7100 and 7200 so there was fine tunability near limiter because drift car. I did narrow the rpm gaps from 500 to 300 as the car built into boost, around 3500 for the same reason.

I tried to use the AEM wideband's analog output as the O2 signal for the ECU. The wideband output was 0-5V but the ECU expected 0-1V, so used a voltage divider from Aliexpress. It worked ok, but i'm now getting a de-cat pipe made up with a flexi & wideband port for the future.


Tuning start & Narrow Throttle:

After setting the 1000 rpm correction factor (idle) when the car was warmed up we noted that during normal "getting up to speed" throttle inputs would go as high as 18%, so we set the Narrow Throttle point to be 20% (any throttle input under 20% would have the Narrow Throttle values)

We then left it in 2nd gear up to 70kmh with light throttle and came to -15% for the correction factor. We filled this in for the rest of the Low Cam and High Cam Narrow Throttle maps and it has been fine.


Tuning Wide Throttle/Low Cam (1000-5700):

Once on the motorway we put it in 4th and let the revs drop to 2000 and started rolling into the throttle, targeting 11:1. After getting the mixtures closer we did a couple of 2000-3500 pulls on full throttle and settled on -7%. We then put -7% in for the rest of the Low Cam/Wide Throttle map and did a pull in 3rd gear all the way through to 5700.


Tuning Wide Throttle/High Cam (5700-7200):

We filled in -7% as a starting point and did a full throttle pull in 2nd gear from 2000-7200. We then did the same in 3rd gear (obviously in Mexico) and noted the extra load had no difference. We did note it go lean on limiter as the stock limiter is a fuel cut, so in the name of longevity we brought the correction factor back up to 0% for the last 3 rpm points


Results:

The car did amazing. The owner beat the living daylights out of it for a day and a half of drifting and it survived.

Retarding the base timing by 5 degrees caused high exhaust temps, melting hoses and wires. As a result we have decided to set it back to 13 degrees and retune, but also to add a boost controller and wind the boost up from 7psi to 12psi, then 15psi. The added boost will give it enough midrange that it will spin the 215 tyres he runs a lot easier, rather than struggle against them with 7psi and load the engine up (car has a 4.3 diff already).

So stay "tuned" for the retune in the coming months (owner is in the middle of buying a house so cars will take a back seat for the coming weeks). I want to feed this thread with all my findings to show people what you can achieve on basic parts

 

[BenRice]

Updated with pics

 

[Ortega]

TOP guide!

Anything that will make a result Can't be hated!

 

[BenRice]

Cheers man. I couldn't find anything on the internet that was similar. I came to the conclusion that the people who knew how easy it was to +T a car either wanted to keep it a secret, or couldn't use a computer or didn't have the time to write it up.

I'm itching to reset the timing, fit the boost controller and do the retune. The owner is going to store the car at mine as he prepares to move into his new place so will get those things knocked out ASAP. If anyone wants photos of other things let me know

 

[thyfartismurder]

The main issue finding a guide like this has been that until recently, you could swap in a DET engine for little extra cost and less hassle then the +T, now with prices on the rise, thats changed.

as DE owner my self I'm very eager for more information on the +T conversion being available!

 

[BenRice]

Agreed. It's the same over here, maybe even further advanced. DET engines are NZD$4-6k for an unopened complete stock motor. That's 100% bone stock, unknown condition turbo etc.

I worked out if you were to purchase all the above (specialist tools, wideband, everything) you'd have a running +T with extras (new HD clutch, new FMIC, new 3" exhaust, new alloy radiator, new Walbro) for less than NZD$3k.

If you purchased items secondhand, like the FMIC kit, exhaust, radiator, etc and borrowed things like the specialist tools then it's more like NZD$1500

Considering you could do all this in a weekend and good condition DE motors are way more common than DET motors it seems a bit of a no brainer. Now I've got the specialist tools and it's a proven combo I've got 2 more people keen to have the same setup done locally, and another keen to do it on an RB20E. Am scouring the Honda classifieds for VAFC's now lol

(halve those figures for GBP btw)

 

[thyfartismurder]

Sounds about the same here with that maths, I could fly you over from NZ to do the conversion cheaper then buying a DET engine
it looks like the only tricky bit is the tuning, which Im guessing would be easier for me as i have a non vvti DE

 

[BenRice]

Just need a mate to jump in the drivers seat and a nice stretch of motorway that isn't too busy you can loop up and down on for an hour.

If you start with correction factors of -15% on the Narrow Throttle and -7% on the Wide Throttle then half the jobs done. It's just a matter of watching the air/fuels all the way through the rev range. A 1% change is quite significant, so the a/f's jump 0.2-0.4

The red top DE's rev a bit higher IIRC. Something like 7600 maybe? But tbh i didn't have to change fuck all at the VCT switch over point. The stock ECU already trims fuel accordingly, so the -7% correction factor was just to adjust for the 370cc injectors and the 7psi of extra air

 

[thyfartismurder]

Thats somthing ill have to do some research on beforehand if i decide to give it a go, but it sounds alot more doable then i expected!

 

[Andrex]

Just curiosity..but how come you have blocked up PCV?

I've run blocked and unblocked and the only difference I found is that when its blocked up, the revs can drop quite low when going to idle.

 

[crazyae86]

well its nice read nice work !!!!

 

[BenRice]

Just curiosity..but how come you have blocked up PCV?

I've run blocked and unblocked and the only difference I found is that when its blocked up, the revs can drop quite low when going to idle.

For us here in NZ we're required to run oil catch cans equal to 50% of the oil capacity of the engine, and block all connections from the oil galleries to the intake if we want to get onto a race track. Race tracks imposed this blanket rule after a number of PCV failures / blown rings which caused oil downs. Oil downs are a headache for them, reduce track time for others and leave a portion of the track in a less than ideal situation for the remainder of the day. Sure, it won't help if you window a block, but it's caught a big number of instances of smaller issues

Also, in my experience PCV's fail over time. A lot of the engines I've worked on over the years are between 20 and 30 years old. I'm just eliminating a possible maintenance-related issue down the road.

well its nice read nice work !!!!

Thanks man.

We're all battling winter flu's here at the moment so no updates yet sorry

 

[matt_23]

Great read great guide, wish this was here for when I started mine haha but if any of you are thinking of doing this conversion I'd without doubt use this guide he's helped me numerous times and knows his stuff.

 

[chidley]

Awesome read there, loads of information to consider.

I will be doing an RB25DE+T at some point in the future but its good to have something like this to refer back to. Thanks!

 

[BenRice]

No worries man. Feel free to fire me any questions when you get into it

I've collected 2x VAFC's and an SAFC since writing this up, and got my hands on a locally made de-cat pipe with a wideband boss & bung already on it.

The S14 in the writeup is getting picked up by the owner this weekend. We haven't reset the timing yet but with any luck we'll do it when he picks it up

 

[SR20scrub]

Awesome guide! I

I've just bought myself a VAFC II for my SR20DE+T conversion and was hoping you could shed some more light on the wiring process!

I'm finding the thought of cutting into my loom quite intimidating so would appreciate a somewhat thorough guide on if or what you've wired the VTC, TDC, VTM, and VTEC solenoids into

I also have a few questions regarding whether to run a DE or DET ecu and loom/ignition system.

The DE motor ive bought came with the DET ECU and loom, so im inclined to run with this, but curious to know your thoughts on which would be better/safer at the end of the day.

Thanks in advance
Much appreciated!

 

[BenRice]

Didn't connect any of those wires

If you have the DET ECU and loom then might be better to use them. You will still need to swap to a CAS instead of a dizzy and get some coilpacks as well. I'd still retard base timing to 12deg BTDC though to take a bit of spice out of the timing to account for the higher compression.

If you do all that & run the factory DET 370cc injectors then you could run it without the VAFC. Just grab a good wideband and check the mixtures in 2nd gear (ie low load) at full throttle. If they go above 12.5:1 then wire in the VAFC and give it some more fuel. If instead the mixtures are all good then do a 3rd gear pull and check again, then if all good still then do a 4th gear run (ie highest load).

Alternatively if you're using the DET ECU then you can use bigger injectors if you fit the VAFC, and shoot for more boost (if the rest of the setup is able to handle it)

 

[BenRice]

So time to update this. I've been messaged a bunch of times on IG so figured I'd pick out the common questions and set the record straight on them:

Q: I'm going to turbo my SR20DE, do I need an aftermarket ECU and tune?
A: No. You can use the factory SR20DE ECU if you fit an Air Fuel Controller (SAFC, SAFC2, VAFC, VAFC2, SAFC NEO etc) to run the larger injectors. These AFC's allow you to alter the AFM signal to the ECU in order to reduce the injector opening times.

You will also need to retard your base timing to 10 degrees BTDC and preferably run E85 or a high octane fuel. If any of this sounds confusing then either do more research and learn what it means or accept you're going to need to pay smarter people to solve your problem

Q: Do I need to use an air flow converter (AFC)?
A: If you want to use bigger injectors, then yes. And i wouldn't run over 3psi without at least an adjustable rising rate FPR on stock injectors. 370cc side feed injectors are cheap as chips as they come out of SR20DET's and RB25DET's

Q: I've filled it with E85, retarded my base timing to 10deg BTDC, fitted 370cc injectors, an adj FPR and an AFC, do i have to take it to a dyno tuner?
A: No. If you're willing to buy a wideband as well then you can tune it yourself with a buddy on a piece of quiet motorway. Use the settings I've described above and work up to it. Check the wideband values on light load in increasing RPM increments. Then start doing 2nd gear full throttle pulls, increasing 1000rpm each time and taking note of the air fuel ratios and adjusting the percentages accordingly. Finish off with some 3rd or 4th (on closed roads....) pulls to simulate max load and as long as those wideband values don't go over 11:1 you're golden.

Q: Can I use a DET computer?
A: Only if you swap the dizzy for a CAS and swap the engine loom for a DET loom and retard the base timing to 10deg BTDC. Finding an unbutchered DET loom and matching ECU can be tricky, as is finding a known working CAS. At that point I'd rather just use a virgin DE loom and good old dizzy & plugs

Q: What about the DE not having oil squirters?
A: If you ensure you have good air/fuel ratios, no knock & run good fuel you'll be fine. If you start pushing beyond 17-18psi you might be asking a bit much but that's when you're moving away from "cheap & cheerful" and should be investing in a standalone anyway. This can't be an all encompassing guide, more for those who are happy to run in the <14psi region/just want choo-choo noises without knock-knock noises

Q: How do I know if my engine is knocking?
A: This is the one thing you can't really check without a dyno tuner & their magical headphones. If you follow the guide (10deg BTDC/air fuel ratio on boost of <11:1/high octane or E85 fuel) then you're using a tried & true recipe that has been put through it's paces successfully. If you're a worry wart like me and want to be double sure, then ask a tuner for a short booking to check for excessive knock. This will be identified in one power run. You can also retard the dizzy a "smidge" (official dyno operator measurements lol) and retest very easily. Give the tuner a heads up you'd like to be able to do this if required, or if he is happy doing it. Any dyno tuner worth his salt will be fine with that but some are MICROTECH/HALTECH/ECUMASTER elitists and don't know what dizzy's are. Worth avoiding those types with a setup like this anyway as you'll no doubt be sold something that'll cost thousands, then hundreds to install, then thousands to tune

Q: Will an Apexi RSM or AVCR do the same job as an SAFC/VAFC?
A: No. RSM's are next to useless, and AVCR's are boost controllers. The screen's look almost the same so don't be fooled

Q: Why do I need to set base timing to 10 degrees BTDC?
A: The DE engines run higher compression & the DE ECU's have more aggressive timing maps than DET ECU's. Retarding the base timing takes the spice out of the DE ECU's timing maps and helps avoid detonation with the higher compression ratio. Retarding the base timing 5 degrees will not rob you of any noticeable power (I have seen this verified on a dyno with back-to-back pulls) and you're adding 20-50% more power through the turbo anyway.

If you have any other questions post them here or fire me a message on IG and I'll update this